Free Engineering Web Tools

Browser-based tools you can use right now — no install, no signup.

Seminar Poster Builder

Create professional seminar posters in minutes — live preview, font controls, image uploads, QR code, one-click PNG export.

Free Web Tool New
  • Editable title, date, time, badge, tagline & topics
  • Per-field font controls (15 typefaces, weight, italic)
  • Hero image, speaker photo & logo upload (with white-bg cutout)
  • Live QR code — encodes any registration URL
  • Resizable hero image, draggable logo positioning
  • Auto-saves your edits in your browser
  • Download as 1200×1800 PNG
Open Poster Builder

Web Builder

Paste your HTML, CSS & JavaScript and see the rendered page live — or open the preview in a new tab.

Free Web Tool New
  • Three editors — HTML, CSS, JavaScript — in one screen
  • Live iframe preview updates as you type (debounced)
  • Open the rendered page in a separate browser tab
  • Smart wrapping: full HTML docs and fragments both work
  • Per-pane Copy buttons & Tab indents two spaces
  • Auto-saves your code in your browser (localStorage)
  • Sandboxed iframe — runs your scripts safely on the page
Open Web Builder

Pipe Sizing Calculator

Size piping for water, steam, compressed air & gas in seconds — instant velocity, pressure drop, and recommended commercial pipe diameter.

Free Web Tool New
  • Supports water, steam, compressed air & gas flows
  • Metric and Imperial units — one-click switch
  • Calculates velocity, Reynolds number & pressure drop
  • Recommends nearest commercial pipe size
  • Editable roughness, fittings & pipe length
  • Mobile-friendly — no install, runs in your browser
Open Pipe Calculator

Tank Volume Calculator

Compute total capacity and liquid volume from level — vertical & horizontal cylindrical, spherical, conical-frustum, and rectangular tanks. Live SVG diagram updates as you type.

Free Web Tool New
  • 5 tank shapes — vertical/horizontal cylinder, sphere, frustum, rectangular
  • Partial-fill volume from liquid depth (slider + numeric input)
  • Live SVG diagram with liquid-level visualization
  • Outputs in L, m³, US/Imperial gallons, ft³
  • Mass-of-water estimate (998 kg/m³ @ 20 °C)
  • Metric / Imperial toggle, mm/cm/m/in/ft units
  • Auto-saves your inputs in your browser
Open Tank Calculator

Beam Calculator

Shear, bending moment and deflection for simply-supported and cantilever beams — multiple load types and live SFD/BMD diagrams.

Free Web Tool New
  • Simply-supported & cantilever beams
  • Point loads, UDL, partial UDL, linear varying, applied moments
  • Live shear force & bending moment diagrams
  • Numerical deflection (E·I) — metric or imperial
  • Reactions, max V, max M, max δ instantly
  • Auto-saves inputs in your browser
Open Beam Calculator

Steel Section Properties

Look up AISC W shapes, channels, angles, HSS and metric universal beams — A, I, S, Z, r plus quick LRFD φMn capacity.

Free Web Tool New
  • AISC W, C, HSS, L (equal angles)
  • Metric Universal Beams & Universal Columns (BS EN)
  • A, Ix, Iy, Sx, Sy, Zx, Zy, rx, ry
  • Quick φMp & φMn with Lb check
  • Section sketch (auto-scaled)
  • Filter by size (e.g. W12, UB406)
Open Steel Lookup

RC Beam Design

Singly-reinforced concrete beam design per ACI 318 / NSCP 2015 — required As, ρ checks, suggested bar combinations and φMn.

Free Web Tool New
  • Whitney stress block, β1 per ACI 318
  • ρmin / ρmax tension-controlled checks
  • Suggested bar combinations (PNS metric or ASTM)
  • Live cross-section with neutral axis
  • Computes a, c, εt, φMn
  • Metric and Imperial units
Open RC Beam Design

Spread Footing Sizer

Size square isolated footings — soil bearing area, one-way and two-way (punching) shear, flexural reinforcement.

Free Web Tool New
  • Required area from allowable bearing qa
  • One-way (beam) shear at d from face
  • Two-way (punching) shear with full ACI Vc envelope
  • Flexural As per direction with bar mat spacing
  • Plan diagram with critical perimeter
  • Pass / Fail status badges
Open Footing Sizer

Concrete & Rebar Estimator

Estimate concrete volume, cement bags, sand, gravel and steel reinforcement weight for slabs, beams, columns, footings and walls.

Free Web Tool New
  • 5 element types + custom — mix & match
  • Mix ratios (Class AA / A / B / C / lean)
  • Configurable cement bag weight (40 kg / 94 lb etc.)
  • Waste / contingency factor
  • Rebar weight estimate (kg/m³ default)
  • Per-item breakdown table
Open Concrete Estimator

Manning’s Open Channel Flow

Solve open-channel flow with Manning’s equation — rectangular, trapezoidal, triangular and circular sections with live cross-section.

Free Web Tool New
  • Solve for Q, normal depth or required slope
  • Rect, trapezoidal, triangular & circular sections
  • n-value presets for common surfaces
  • Hydraulic radius, top width, Froude number
  • Subcritical / supercritical regime detection
  • Live SVG cross-section with water level
Open Manning’s Flow

Stormwater Runoff (Rational)

Peak runoff using Q = CIA — multi-surface areas with weighted C, Kirpich time-of-concentration and metric/imperial outputs.

Free Web Tool New
  • Add unlimited sub-areas with surface presets
  • Auto weighted runoff coefficient C
  • Kirpich tc from L & H (or override)
  • Metric (mm/h, ha) and Imperial (in/h, ac)
  • Outputs Q in m³/s and cfs
  • Per-area breakdown table
Open Runoff Calculator

Closed Traverse & Area

Bearings & distances → coordinates, closure error, balanced area — with live SVG plot of the traverse.

Free Web Tool New
  • Quadrant bearings (N 45 30 E) or azimuth
  • Compass (Bowditch) rule balancing
  • Coordinate-method (shoelace) area
  • Closure error & precision (1:N)
  • Live plot with point labels & north arrow
  • Per-line ΔN, ΔE, N, E table
Open Traverse Calculator

Highway Curve Calculator

Horizontal circular curves and vertical parabolic curves — T, L, M, E, K, BVC/EVC, sight distance and station report.

Free Web Tool New
  • Horizontal: T, L, LC, M, E, PC, PT, degree of curve
  • Vertical: K-value, BVC/EVC, turning point, mid elevation
  • SSD-based minimum L (AASHTO crest & sag)
  • Right / left deflection direction
  • Station format output (e.g. 12+345.67)
  • Live diagram for both curve types
Open Highway Curve

Soil Bearing Capacity

Terzaghi (1943) and Meyerhof (1963) ultimate & allowable bearing capacity for shallow footings — strip, square, rectangular, circular.

Free Web Tool New
  • Both Terzaghi & Meyerhof Nc, Nq, Nγ
  • Shape, depth and water-table corrections
  • Strip, square, rectangular & circular footings
  • Cohesion, surcharge & self-weight terms broken out
  • Allowable qa (gross & net) with FS
  • Section diagram with failure surface
Open Bearing Capacity

Wind Load Calculator

ASCE 7-22 / NSCP 2015 directional procedure (MWFRS) — design wind pressures for windward, leeward, side and roof faces.

FreeWeb ToolNew
  • Exposure B / C / D + risk category
  • Auto Kz and velocity pressure qh
  • Windward, leeward, side, roof Cp
  • Internal pressure GCpi ± both signs
  • Worst-case net pressure per face
  • Metric (m/s, Pa) & Imperial (mph, psf)
Open Wind Calculator

Seismic Base Shear (ELF)

Equivalent Lateral Force per ASCE 7-22 / NSCP 2015 — base shear V from SDS, SD1, R, Ie, with floor Fx distribution.

FreeWeb ToolNew
  • Auto Ta = Ct·hnx
  • Cs with upper, lower, TL limits
  • Risk category Ie auto
  • Multi-floor weight + height table
  • Vertical distribution exponent k auto-interp
  • Fx per level table
Open Seismic Calculator

Load Combinations

All ASCE 7 / NSCP 2015 LRFD & ASD load combinations evaluated instantly — controlling case and demand highlighted.

FreeWeb ToolNew
  • LRFD & ASD with one click
  • D, L, Lr, S, R, W, E, F inputs
  • 0.5L / 1.0L threshold automatic
  • Both wind & seismic signs evaluated
  • Controlling combo highlighted
  • Full table of all combinations
Open Load Combos

Cantilever Retaining Wall

Stability (sliding, overturning, bearing) plus stem flexure/shear — Rankine active & passive, surcharge, base friction.

FreeWeb ToolNew
  • Full geometry: stem trapezoid, base, toe, heel
  • FS sliding, overturning auto-checked
  • Bearing qmax / qmin trapezoidal
  • Eccentricity vs B/6 kern
  • Stem M / V at base
  • Live cross-section diagram
Open Retaining Wall

Pile Capacity (Axial)

α-method (clay) and β-method (sand) skin friction plus end bearing in layered soil — ultimate & allowable capacity, capacity vs depth chart.

FreeWeb ToolNew
  • Layered soil profile (clay / sand mix)
  • API α (auto from su) for clay
  • β·σ'v for sand with K·tanδ default
  • End bearing: 9·su (clay) or σ'·Nq (sand)
  • Effective stress with water table
  • Per-layer skin friction breakdown
Open Pile Capacity

Lateral Earth Pressure

Active, passive, at-rest pressures (Rankine & Coulomb) with surcharge, water table, cohesion — resultant force and pressure diagram.

FreeWeb ToolNew
  • Rankine & full Coulomb K equations
  • Active, passive, at-rest states
  • Tension crack depth zc for c > 0
  • Surcharge & water-table contributions
  • Total resultant P and y̅ from base
  • Live pressure-diagram render
Open LEP Calculator

Consolidation Settlement

1-D primary consolidation settlement of clay using e₀, Cc, Cr with NC / OC handling, plus time-rate from Cv and Tv.

FreeWeb ToolNew
  • NC / OC / OC-with-exceedance branching
  • Total primary settlement S
  • Tv ↔ U(t) Casagrande approximation
  • Single or double drainage
  • Settlement at user time t
  • Time table for U = 10, 25, 50, 70, 90, 95, 99%
Open Consolidation

RC Column P-M Interaction

Generate the φP-φM interaction diagram for tied rectangular RC columns — plot load points and check capacity.

FreeWeb ToolNew
  • Strain-compatibility interaction diagram
  • Pure compression cap (0.80 / 0.85 P0)
  • Balanced point + pure flexure
  • φ varies with εt (per ACI 318)
  • Load point inside/outside check
  • Tied or spiral reinforcement
Open Column Interaction

Two-Way Slab — DDM

Direct Design Method per ACI 318 / NSCP 2015 — min thickness, total static moment M0, distribution to spans & column / middle strips.

FreeWeb ToolNew
  • Interior & exterior panel coefficients
  • Auto factored load 1.2D + 1.6L
  • M0 = wu·ℓ2·ℓn²/8
  • Negative / positive moment split
  • Column-strip vs middle-strip distribution
  • Min thickness check
Open Two-Way Slab

Anchor Bolt & Base Plate

Concentric base plate sizing (LRFD), anchor tension demand from column moment, plus ACI 318 Ch. 17 anchor steel & concrete breakout checks.

FreeWeb ToolNew
  • Eccentricity / kern check (e vs N/6)
  • Bearing length Y & anchor tension T
  • Plate thickness from cantilever bending
  • Anchor steel φNsa / φVsa
  • Concrete breakout φNcb (cast-in)
  • Plan-view diagram with anchors
Open Anchor / Base Plate

Bolt Group — Eccentric

Elastic vector method for in-plane eccentric bolt groups — direct & torsional shear, controlling bolt and design check.

FreeWeb ToolNew
  • Custom bolt patterns or quick 2×2 / 3×3 grids
  • Auto centroid & polar moment J
  • Per-bolt resultant force & controlling bolt
  • Demand vs φRn capacity
  • Live bolt-pattern + load arrow diagram
  • Load angle θ supported
Open Bolt Group

2D Truss Analyzer

Method of Joints solver — define nodes, members, supports & loads → reactions and member forces with color-coded T/C diagram.

FreeWeb ToolNew
  • Static determinacy auto-checked
  • Pin / roller-y / roller-x supports
  • Linear-system solver (Gaussian)
  • T (tension) / C (compression) badges
  • Color & thickness scaled by force magnitude
  • Reaction table
Open Truss Analyzer

Fillet Weld Capacity

AISC LRFD fillet weld design — strength per length, total capacity, with optional load-angle increase factor and base-metal shear check.

FreeWeb ToolNew
  • E60–E90 electrodes
  • (1.0 + 0.5 sin¹·⁵θ) load-angle increase
  • Base metal shear rupture check
  • Required length Lreq
  • Demand / capacity ratio
  • Metric or Imperial units
Open Fillet Weld

Culvert Sizing (HDS-5)

Inlet- and outlet-control headwater for circular & box culverts following FHWA HDS-5 simplified method, controlling type reported.

FreeWeb ToolNew
  • Concrete pipe / CMP / concrete box
  • Square / groove / projecting inlets
  • Inlet vs outlet control comparison
  • Tailwater & entrance loss
  • Velocity, Hydraulic radius, headwater
  • HW/D ratio reported
Open Culvert Sizer

Weir & Orifice Flow

Discharge from rectangular & V-notch weirs, broad-crested weirs and free-flow orifices — instant Q for any geometry.

FreeWeb ToolNew
  • Rectangular sharp-crested (Rehbock Cd)
  • V-notch (any θ)
  • Broad-crested weir
  • Orifice (free-flow)
  • Optional Cd override
  • Metric & imperial outputs
Open Weir / Orifice

Detention Pond Sizing

Required storage volume by Modified Rational Method — sweep storm durations to find the controlling required storage.

FreeWeb ToolNew
  • IDF: i = a/(t+b)n
  • Sweeps duration td
  • Controlling td* & V*
  • Equivalent depth over watershed
  • m³ ↔ acre-ft conversion
  • Required-storage curve plot
Open Detention Pond

Pipe Network — Hardy Cross

Hazen-Williams loop-iteration solver for looped distribution networks. Define pipes & loops, get balanced flows.

FreeWeb ToolNew
  • Multi-loop (signed pipe sequence)
  • Auto correction Δ per loop
  • Configurable tolerance & iter limit
  • Final Q, V, hL per pipe
  • Convergence status
  • Per-loop residuals
Open Hardy Cross
CN

SCS Curve Number Runoff

Composite Curve Number from sub-areas + HSG, then runoff Q from rainfall depth (NEH-4 / TR-55) with AMC adjustment.

FreeWeb ToolNew
  • 16 land-use presets × 4 HSG
  • Multi-area composite CN
  • AMC I / II / III adjustment
  • S = 25400/CN − 254 (mm)
  • Runoff depth Q and volume V
  • Initial abstraction Ia reported
Open SCS CN Runoff

Time of Concentration

Side-by-side tc from five common methods — Kirpich, Bransby-Williams, NRCS lag, Kerby and TR-55 channel V — for direct comparison.

FreeWeb ToolNew
  • Kirpich (channel)
  • Bransby-Williams (rural)
  • NRCS lag (TR-55)
  • Kerby overland (with retardance)
  • TR-55 channel velocity
  • Median recommended tc
Open Tc Calculator

Earthwork Volume

Average end-area & prismoidal volumes from a station table of cut/fill — cumulative net volume and mass-haul diagram.

FreeWeb ToolNew
  • Average end-area (AEA) or prismoidal
  • Station+offset (e.g. 0+100) parsing
  • Shrinkage / bulking factor on fill
  • Cut, Fill and Net totals
  • Per-segment + cumulative table
  • Mass-haul diagram (cumulative net)
Open Earthwork

Superelevation Calculator

Required e for design speed & curve radius (AASHTO), plus runoff length and tangent runout for the lane width.

FreeWeb ToolNew
  • e + f = V²/(127·R) (metric / imperial)
  • emax 4–12% selectable
  • AASHTO side friction f auto-interpolated
  • Min radius Rmin reported
  • Runoff length & tangent runout
  • e > emax warnings
Open Superelevation

Pavement Design (AASHTO 93)

Required Structural Number SN from ESALs, reliability, MR, ΔPSI — then split SN among AC, base and subbase layers.

FreeWeb ToolNew
  • AASHTO 1993 design equation solver
  • ZR auto-interpolated from R%
  • 2-layer or 3-layer split
  • Drainage coefficients m2, m3
  • Recommended layer thicknesses
  • Provided vs required SN check
Open AASHTO 93

Coordinate Inverse

Distance and bearing/azimuth between any two N,E points. Single inverse plus a sequential point-list table.

FreeWeb ToolNew
  • Single-pair inverse
  • Multi-point list with sequential inverses
  • Quadrant or azimuth output
  • Distance + ΔN + ΔE
  • DMS notation for quadrant bearings
  • Auto-saves your point list
Open Coord. Inverse

Differential Leveling

Reduce a level book — Height of Instrument or Rise & Fall, with arithmetic check and loop closure.

FreeWeb ToolNew
  • BS / FS / IS observations per row
  • HI & RL columns auto-computed
  • ΣBS − ΣFS arithmetic check
  • Closure error (mm) with known final BM
  • Turning points (FS + BS on same row)
  • Friendly text-table input
Open Diff. Leveling

Curve Stake-out

Field stake-out for a circular curve — chord deflection angles from PC and N, E coordinates of every station.

FreeWeb ToolNew
  • Configurable station interval
  • PT included automatically
  • Right or left deflection
  • Deflection angle in DMS
  • Chord length from PC
  • N, E coords from PC + back-azimuth
Open Stake-out

Bearing & DMS Calculator

DMS ↔ decimal, quadrant ↔ azimuth, bearing arithmetic (add / subtract / interior angle), plus radians and gradians.

FreeWeb ToolNew
  • DMS to decimal degrees
  • Decimal to DMS
  • Quadrant ↔ azimuth
  • Add / subtract / interior angles
  • Back-bearing (azimuth + 180°)
  • Radians + gradians outputs
Open Bearing / DMS

Engineering Unit Converter

Length, area, volume, mass, force, pressure, moment, density, flow, energy, power, temperature, velocity & viscosity — all in one.

FreeWeb ToolNew
  • 14 engineering quantity types
  • Comprehensive unit lists per quantity
  • Live multi-unit table (all conversions at once)
  • Temperature: °C, °F, K, R
  • Pressure: Pa, MPa, psi, ksi, bar, atm…
  • Auto-saves last selection
Open Unit Converter

Slope Converter

Translate between %, ratio (1:n), angle (°), V:H and rise/run for any input form — live cross-section sketch.

FreeWeb ToolNew
  • Input as %, ratio, angle, rise/run
  • All other forms computed instantly
  • Both V:H and H:V notations
  • Degrees and radians
  • Rise per 100 m run
  • Live triangle sketch
Open Slope Converter

Development & Splice Length

ACI 318 development length for tension/compression bars, hooks, and Class A/B lap splices — with all ψ factors.

FreeWeb ToolNew
  • Tension & compression development
  • 90° hook anchorage
  • Class A & Class B splices
  • ψt, ψe, ψs, λ factors
  • Bar sizes 10–40 mm
  • Min length governs auto
Open Dev/Splice

Crack Width & Serviceability

Estimate RC beam crack width using the Gergely & Lutz expression (ACI 224R) and compare with exposure-class limits.

FreeWeb ToolNew
  • Gergely-Lutz formula
  • Effective tension area A
  • Top/bottom bar β factor
  • 3 exposure classes
  • Service stress fs input
  • Pass/fail vs allowable
Open Crack Width

One-Way Slab Design

Design a one-way RC slab — minimum thickness, factored moment, required steel and bar spacing per ACI 318.

FreeWeb ToolNew
  • Code minimum thickness h
  • Factored Wu, Mu
  • As required (mm²/m)
  • Bar spacing & max
  • Shrinkage steel
  • Span continuity options
Open One-Way Slab

RC Shear Wall Design

In-plane shear and reinforcement check for cast-in-place concrete shear walls per ACI 318 §11.5 with boundary-element flag.

FreeWeb ToolNew
  • Vc + Vs capacity
  • φVn vs Vu DCR
  • ρt and ρl reinforcement
  • Upper limit Vmax
  • Boundary element flag
  • Axial + flexure aware
Open Shear Wall

Punching Shear (Two-Way)

Two-way punching shear capacity around a column for slabs per ACI 318 §22.6 — interior, edge, corner.

FreeWeb ToolNew
  • b₀ critical perimeter
  • 3 vc terms governing
  • Interior/edge/corner
  • φVc vs Vu DCR
  • β & αs auto
  • Stirrup / drop panel hint
Open Punching Shear

Combined Footing Sizer

Two-column rectangular footing sized by the resultant-of-loads method to keep soil pressure uniform.

FreeWeb ToolNew
  • Resultant location ̄x
  • Required L & B
  • Provided pressure
  • Edge distance input
  • Pass/fail vs qa
  • Auto width recheck
Open Combined Footing

Mat (Raft) Foundation

Soil contact pressures and approximate settlement for a rigid mat/raft under biaxial eccentricity.

FreeWeb ToolNew
  • q_max / q_min check
  • Biaxial eccentricity ex/ey
  • Settlement δ ≈ q/ks
  • Tension/uplift flag
  • Modulus of subgrade
  • Mat thickness input
Open Mat Foundation

Concrete Mix Design (ACI 211)

Proportion concrete mix per ACI 211.1 — water, w/c, cement, coarse and fine aggregate by absolute volume per m³.

FreeWeb ToolNew
  • ACI 211.1 method
  • Water by Dmax + slump
  • w/c from Abrams
  • Aggregate by abs. vol.
  • Air-entrained option
  • Mass per m³ output
Open Mix Design

Bar Bending Schedule (BBS)

Build a BBS — cut lengths with bend deductions, total weight per the d²/162 rule, and CSV export.

FreeWeb ToolNew
  • Cut length w/ bends
  • d²/162 weight rule
  • Add multiple marks
  • By-size totals
  • CSV download
  • Auto-saves locally
Open BBS Generator

Steel Column Buckling

AISC 360 §E3 column compression capacity — Fe, Fcr, φPn for elastic and inelastic buckling.

FreeWeb ToolNew
  • AISC 360 §E3 method
  • Auto elastic / inelastic
  • Fy presets (A36, A992, A572)
  • Effective length K presets
  • φPn (LRFD)
  • Mode reported
Open Column Buckling

Composite Beam

Plastic moment capacity and stud count for steel-concrete composite beams per AISC 360-I.

FreeWeb ToolNew
  • Cconc / Tsteel governing
  • Stress block a
  • Studs per half/full span
  • Full or partial composite
  • Plastic Mn
  • Effective slab width input
Open Composite Beam

Bolted Shear Connection

Capacity check per AISC 360 §J3 — bolt shear, plate bearing, and tearout, governing case identified.

FreeWeb ToolNew
  • A325, A490, A307 grades
  • N or X shear plane
  • Bearing & tearout
  • Per-bolt and total
  • Edge distance Le
  • Mode (shear/bearing/tearout)
Open Bolted Shear

Beam Deflection

Closed-form deflection, moment, and shear for common load cases — simple, cantilever, fixed.

FreeWeb ToolNew
  • 6 standard load cases
  • Mmax & Vmax
  • Mid-span δ
  • L/δ ratio
  • Custom E and I
  • Instant recalc
Open Beam Deflection

Built-Up Section Properties

Sum rectangular plates to compute centroid, moment of inertia, section modulus and radius of gyration.

FreeWeb ToolNew
  • Add/remove plates live
  • Parallel-axis theorem
  • Ix, Iy, Sx, rx, ry
  • Centroid plot
  • Live SVG diagram
  • Auto-saves locally
Open Section Builder

Slope Stability — Bishop

Single trial-circle factor of safety using Bishop’s simplified method — for preliminary slope assessment.

FreeWeb ToolNew
  • Bishop simplified iteration
  • c-φ soils with γ & ru
  • 20+ slice subdivision
  • Trial circle radius
  • Stable / marginal flag
  • Closed-form formula trace
Open Slope Stability

USCS / AASHTO Classification

Classify soil per USCS (ASTM D2487) and AASHTO M145 with Cu, Cc, plasticity index, and group index.

FreeWeb ToolNew
  • USCS symbol per ASTM
  • AASHTO group + GI
  • Plasticity chart A-line
  • Cu & Cc auto
  • Atterberg limits in
  • Coarse vs fine grained
Open Soil Class

Sieve Analysis & Gradation

Plot a semi-log gradation curve from sieve % passing data and compute D10, D30, D60, Cu, Cc.

FreeWeb ToolNew
  • 13-sieve standard set
  • Live semi-log plot
  • D10 / D30 / D60
  • Cu & Cc
  • Well/poorly graded
  • Editable in-table
Open Sieve Analysis

Proctor Compaction (MDD/OMC)

Plot dry density vs moisture content and find Maximum Dry Density and Optimum Moisture by quadratic fit.

FreeWeb ToolNew
  • Add unlimited points
  • Quadratic LS fit
  • MDD & OMC peak
  • Live γ_dry plot
  • γ_wet → γ_dry auto
  • Standard / Modified inputs
Open Proctor

CBR Calculator

California Bearing Ratio for laboratory loads at 2.5 / 5.0 mm or direct field readings, with subgrade rating.

FreeWeb ToolNew
  • Lab or field method
  • 2.5 mm and 5.0 mm
  • Standard piston loads
  • Soaked / unsoaked toggle
  • Subgrade rating
  • ASTM D1883
Open CBR

Sheet Pile (Cantilever)

Preliminary embedment depth and approximate maximum moment for cantilever sheet pile in cohesionless soil.

FreeWeb ToolNew
  • Granular soil, c=0
  • Ka, Kp, embedment d
  • FS-applied design depth
  • Total length L
  • Mmax estimate
  • Surcharge q input
Open Sheet Pile

Liquefaction Potential (SPT)

Simplified seismic liquefaction potential per NCEER (Youd et al.) with SPT-based CRR, CSR and FoS.

FreeWeb ToolNew
  • NCEER 2001 procedure
  • σv, σv\u2032 with GWT
  • (N1)60cs fines correction
  • MSF for Mw
  • CRR vs CSR
  • FoS & status
Open Liquefaction

Pump Head & NPSH

Total Dynamic Head and Available NPSH for centrifugal pump sizing — Hazen-Williams losses with minor coefficients.

FreeWeb ToolNew
  • Hazen-Williams Hf
  • Static + dynamic head
  • NPSHa with vapor pressure
  • Minor losses Σ K·Vh
  • Required pump kW
  • Pipe ID input
Open Pump Head

Water Hammer (Joukowsky)

Joukowsky surge head and pressure for sudden valve closure with slow-closure (Michaud) check.

FreeWeb ToolNew
  • Joukowsky ΔH = aV/g
  • Slow closure 2LV/(g·tc)
  • Critical 2L/a
  • Surge ΔP in kPa
  • Material wave speeds
  • Total max head
Open Water Hammer

Sanitary Sewer Design

Pipe sizing for gravity sanitary sewers using Manning’s equation, peak factor, and partial-flow ratios.

FreeWeb ToolNew
  • Population × LPCD × PF
  • Q_full from Manning
  • d/D partial flow
  • Self-cleansing 0.6 m/s
  • Max V check 3.0 m/s
  • Flow ratio table
Open Sanitary Sewer

Water Demand (Fixture Units)

Sum fixture units across plumbing fixtures and convert to peak demand using Hunter’s method.

FreeWeb ToolNew
  • 11 standard fixtures
  • UPC/IPC FU values
  • Hunter peak Q curve
  • Required pipe ID at 2 m/s
  • Avg daily est.
  • Auto-saves locally
Open Water Demand

Backwater (Direct Step)

Compute gradually-varied flow profile in a trapezoidal channel using the direct-step method.

FreeWeb ToolNew
  • Trapezoidal channel
  • Normal & critical depths
  • Profile classification (M1-S3)
  • Step-by-step table
  • Direct-step Δx
  • Manning friction
Open Backwater

Gutter & Inlet (HEC-22)

Gutter flow Q and curb-opening intercept length per HEC-22, with inlet efficiency for partial L.

FreeWeb ToolNew
  • Gutter Q from spread T
  • Curb opening LT
  • Inlet efficiency E
  • Bypass flow
  • Cross & long. slopes
  • HEC-22 method
Open Gutter / Inlet

Vertical Curve (Crest / Sag)

Compute crest or sag vertical curve geometry — A, K, BVC/EVC, high/low point, and minimum L for design SSD.

FreeWeb ToolNew
  • Crest & sag
  • K-value & A
  • BVC / EVC stations
  • High/low point at x
  • Min L for SSD
  • AASHTO formulas
Open Vertical Curve

Sight Distance (SSD / PSD)

AASHTO Stopping Sight Distance with grade and friction adjustment, plus a Passing Sight Distance estimate.

FreeWeb ToolNew
  • SSD with grade ±
  • Reaction + braking
  • PSD estimate
  • Friction f input
  • km/h or mph mental
  • AASHTO formulas
Open Sight Distance

Signal Timing (Webster)

Optimum cycle length and per-phase effective green using Webster’s formula. Add lane-group critical flow ratios.

FreeWeb ToolNew
  • Webster optimum C₀
  • Add unlimited phases
  • Y = Σy ratios
  • Per-phase greens
  • Cycle min/max bounds
  • Auto round to 5s
Open Signal Timing

Pavement Design (DPWH/AASHTO 93)

Solve for required Structural Number SN via AASHTO 93 with reliability, S₀, ΔPSI, Mr.

FreeWeb ToolNew
  • AASHTO 93 SN equation
  • Reliability Z_R lookup
  • Mr from CBR
  • Bisection search
  • Layer thickness suggest
  • DPWH-style output
Open Pavement Design

Mass Haul Diagram

Build a cumulative mass-haul diagram from station volumes — identify cut/fill balance, borrow/waste, and overhaul ranges.

FreeWeb ToolNew
  • Add stations live
  • Cumulative ordinate
  • Net cut/fill
  • Borrow vs waste
  • SVG mass-haul plot
  • Auto-saves locally
Open Mass Haul

Coordinate Forward (Bearing-Distance)

Compute new coordinates from a starting point using bearings and distances — quadrant or azimuths, with traverse plot.

FreeWeb ToolNew
  • Quadrant or azimuth
  • DMS or decimal
  • Add unlimited legs
  • ΔE / ΔN per leg
  • Closing N, E
  • Live SVG plot
Open Coordinate Fwd

Three-Point Resection

Locate an unknown station P from three known stations and two observed angles using Tienstra’s formula.

FreeWeb ToolNew
  • Tienstra barycentric
  • 3 known points
  • 2 observed angles
  • Auto angles ABC
  • Free station
  • Surveyor classic
Open Resection

UTM ↔ Geographic Converter

Convert between UTM and geographic on WGS84 or PRS92 with zone, grid convergence, and scale factor.

FreeWeb ToolNew
  • Lat/Lon → UTM
  • UTM → Lat/Lon
  • WGS84 & PRS92
  • Auto-zone
  • Convergence γ
  • Scale factor k
Open UTM Converter

Earthwork — Cross Sections

Compute earthwork volume from cross-section areas using Average End Area and Prismoidal methods.

FreeWeb ToolNew
  • Avg End Area V
  • Prismoidal V
  • Prismoidal correction
  • Add unlimited stations
  • Auto-saves
  • Sortable stations
Open Earthwork XS

BOQ & Cost Estimator

Build a quick Bill of Quantities — line items, OH&P markup, VAT, grand total, and CSV export.

FreeWeb ToolNew
  • Add unlimited line items
  • Auto subtotal
  • OH&P %
  • VAT %
  • Currency symbol
  • CSV export
Open BOQ Estimator

Productivity Calculator

Estimate daily output for a crew (and equipment) and convert a total quantity into days and weeks.

FreeWeb ToolNew
  • Crew & equipment combined
  • Efficiency factor
  • Days & weeks
  • Cycles/hour mode
  • Hours/day input
  • Auto recalc
Open Productivity

S-Curve / Cash Flow

Generate a planned S-curve and weekly cash flow from project duration, contract amount, and shape factor.

FreeWeb ToolNew
  • Standard / steep / linear
  • Weekly cash table
  • SVG cumulative plot
  • Front-loading shift
  • Currency formatted
  • Mid-point week
Open S-Curve

CPM Float & Critical Path

Add activities with predecessors and durations — computes ES, EF, LS, LF, total float, and the critical path.

FreeWeb ToolNew
  • Forward + backward pass
  • Total Float per activity
  • Auto critical path
  • Project duration
  • CSV-style table
  • Auto-saves locally
Open CPM Float

Shear & Moment Diagram

Add point and distributed loads on a simple-span or cantilever beam — live shear and moment diagrams.

FreeWeb ToolNew
  • Simple span / cantilever
  • Mix point + UDL
  • Live V & M plots
  • Reactions, Vmax, Mmax
  • Add unlimited loads
  • Auto-saves locally
Open SMD

Mohr’s Circle

Compute principal stresses, max shear, and principal/shear angles from σx, σy, τxy — with full SVG plot.

FreeWeb ToolNew
  • σ₁, σ₂ & τmax
  • Principal angle θp
  • Max-shear angle θs
  • Live SVG plot
  • X / Y stress points
  • Real-time recompute
Open Mohr’s Circle

Multi-Span (Continuous) Beam

Solve a continuous beam with the Three-Moment Theorem — support moments, reactions, approximate Mmax.

FreeWeb ToolNew
  • Three-Moment equations
  • Linear-system solver
  • UDL per span
  • Auto reactions
  • Support moments
  • Pinned ends
Open Multi-Span

Load Path Estimator

Trace gravity loads from slab through beam, column, and foundation for rapid take-offs and column sizing.

FreeWeb ToolNew
  • Slab → Beam → Column
  • Tributary area / length
  • # floors above
  • Cumulative base load
  • Foundation factored
  • Quick take-off
Open Load Path

Prestressed Beam Stress Check

Top & bottom fiber stresses at transfer and service for a prestressed beam — with ACI 24.5 allowable comparison and Class U/T/C handling.

FreeWeb ToolNew
  • Transfer + service stresses
  • P_eff = η · P_i (loss ratio)
  • Allowable f_ti, f_ci, f_ts, f_cs
  • Class U / T / C
  • OK / NG verdict
  • Tendon eccentricity sketch
Open Prestressed Beam

Long-Term Deflection (λΔ)

Creep + shrinkage multiplier λΔ = ξ / (1 + 50ρ′) per ACI 318 §24.2.4 with full long-term + sustained deflection check.

FreeWeb ToolNew
  • Duration: 3-mo to 5-yr ξ
  • Compression-steel ρ′
  • Sustained LL fraction
  • L/180, L/240, L/360, L/480
  • Total & long-term Δ
  • OK / NG verdict
Open Long-Term Deflection

Deep Beam — Strut-and-Tie

Single-span deep beam with concentrated load — solves strut angle, strut/tie forces, and required tie steel per ACI 318 Ch. 23.

FreeWeb ToolNew
  • ℓn/h aspect check
  • Strut angle θ
  • Strut + tie forces
  • Required tie As
  • βs / βn factors
  • Truss model sketch
Open Deep Beam

Corbel / Bracket Design

ACI 318 §16.5 corbel sized for Vu and Nuc — computes Avf (shear-friction), An (tension), Af (flexure), As main, and Ah closed stirrups.

FreeWeb ToolNew
  • a/d ≤ 1.0 enforced
  • Avf, An, Af, As main
  • Ah ≥ 0.5(As−An)
  • ϕVn cap (3 limits)
  • μ & λ selectors
  • OK / NG verdict
Open Corbel

Shear-Friction (Cold Joint)

ACI 318 §22.9 shear-friction across cold joints, dapped ends, and corbel interfaces — required Avf and ϕVn cap with all four code limits.

FreeWeb ToolNew
  • μ from interface type
  • λ for lightweight
  • Avf required
  • 0.2 f′c, (3.3+0.08f′c), 11 caps
  • Vu / ϕVn ratio
  • OK / NG verdict
Open Shear-Friction

Diaphragm Force Fpx

Floor-by-floor diaphragm design force per ASCE 7 §12.10 / NSCP with min and max bounds, plus chord tension estimate.

FreeWeb ToolNew
  • Per-level Fpx table
  • 0.2 SDS Ie wpx min
  • 0.4 SDS Ie wpx max
  • Diaphragm M & chord T
  • Add/remove levels
  • Persists locally
Open Diaphragm Fpx

Seismic Detailing Checker (SMF)

Beam & column ductile detailing per NSCP Ch. 4 / ACI 318 Ch. 18 — hoop spacing, hinge zone length, lap-splice exclusion zones.

FreeWeb ToolNew
  • Beam / column modes
  • Hinge zone 2h or ℓ₀
  • s_max = min(b/4, 6 d_b, s₀)
  • Outside hinge limits
  • Min cross-section
  • PASS / CHECK verdict
Open Seismic Detailing

Beam-Column H1-1

AISC 360 §H1.1 combined axial + biaxial bending interaction (auto-picks H1-1a vs H1-1b by Pr/Pc).

FreeWeb ToolNew
  • H1-1a / H1-1b auto
  • Biaxial bending
  • Pr/Pc threshold
  • DCR with verdict
  • LRFD ϕ Pn, ϕb Mn
  • Persists locally
Open Beam-Column

Lateral-Torsional Buckling

AISC 360 §F2 LTB capacity for I-shapes — yielding / inelastic / elastic regions with auto Cb amplification.

FreeWeb ToolNew
  • Cb auto from M(L/4, L/2, 3L/4)
  • Lp / Lr regions
  • Mp = Z·Fy
  • Inelastic LTB line
  • ϕb = 0.90
  • Cb override
Open LTB

Plate Girder Slenderness

Web/flange slenderness and bending-strength reduction Rpg for slender-web doubly-symmetric I-shapes per AISC §F5.

FreeWeb ToolNew
  • λw = h/tw
  • λp / λr limits
  • Web class
  • Rpg ≤ 1.0
  • Mn = Rpg·Fy·Sx
  • ϕb Mn
Open Plate Girder

HSS T/Y Joint

Axially-loaded branch on rectangular HSS chord — chord plastification, punching shear, sidewall yielding per AISC 360 Ch. K.

FreeWeb ToolNew
  • β, η ratios
  • Plastification
  • Punching shear
  • Sidewall yielding
  • Branch angle θ
  • DCR verdict
Open HSS Joint

Block Shear Rupture

AISC 360 §J4.3 block-shear capacity at bolted gusset and angle-leg connections — Rn = min of two failure paths.

FreeWeb ToolNew
  • Anv, Agv, Ant inputs
  • Ubs uniform / non-uniform
  • Two failure paths
  • Rn governing
  • ϕ = 0.75
  • DCR vs Pu
Open Block Shear

Web Yielding & Crippling

AISC 360 §J10 concentrated-force checks — local web yielding, web crippling, and compression buckling at I-shape webs.

FreeWeb ToolNew
  • Yielding J10.2
  • Crippling J10.3
  • Buckling J10.5
  • Interior or end
  • Three ϕ values
  • Governing limit
Open Web J10

Cold-Formed Z/C Purlin

Laterally-braced Z and C purlin moment capacity per AISI S100, with Mu vs ϕb Mn and L/180 deflection check.

FreeWeb ToolNew
  • Z150–Z250, C200–C250
  • Effective Se proxy
  • LRFD wu = 1.2D + 1.6L
  • Δ_LL vs L/180
  • Tributary spacing
  • Per-purlin Mu
Open Cold-Formed Purlin

Moment End-Plate

Four-bolt unstiffened end-plate moment connection — bolt tension demand, plate thickness via yield-line, and weld sizing.

FreeWeb ToolNew
  • Lever arm h
  • Flange tension Tf
  • Per-bolt T_b
  • ϕ Rn,bolt (A325/A490)
  • tp from yield-line
  • Weld sizing guide
Open End-Plate

Pile Group Capacity

Group efficiency by Converse-Labarre, Feld, and Seiler-Keeney with block-failure check for cohesive soils.

FreeWeb ToolNew
  • m × n grid
  • 3 efficiency methods
  • Block failure (cohesive)
  • Spacing s, diameter D
  • Governing capacity
  • Persists locally
Open Pile Group

Drilled Shaft / Bored Pile

Axial capacity of drilled shafts in cohesive (α-method) and cohesionless (β-method) soils with shaft + tip resistance.

FreeWeb ToolNew
  • α-method (cohesive)
  • β-method (cohless)
  • Tip + shaft
  • Caps on qt
  • Allowable Qa
  • FS = 2.5 default
Open Drilled Shaft

Bearing Capacity Comparator

Side-by-side ultimate bearing capacity from Terzaghi, Meyerhof, Hansen, and Vesic with shape factors and allowable q_a.

FreeWeb ToolNew
  • 4 methods at once
  • Strip / Sq / Rect / Circ
  • Bearing factors auto
  • Shape factors
  • Average q_ult
  • q_allow with FS
Open Bearing Comparator

MSE Wall Internal Stability

Per-layer reinforcement Tmax, pullout resistance and FS_po for steel-strip MSE walls per FHWA NHI-10-024 simplified method.

FreeWeb ToolNew
  • Ka simplified Kr
  • Tmax = σh·Sv
  • Pullout Pr
  • F* and α
  • FS_po ≥ 1.5
  • Strip yield t_req
Open MSE Wall

Seepage Flow Net

Seepage discharge Q from flow-net counts (Nf, Nd) plus exit gradient i_e and FS against piping.

FreeWeb ToolNew
  • q = k·H·Nf/Nd
  • Δh per drop
  • Exit gradient i_e
  • Critical i_c
  • FS ≥ 3.0 piping
  • k in m/s
Open Seepage

Immediate Settlement

Elastic settlement of shallow foundations — Schmertmann strain-influence and Mayne-Poulos closed-form, with the lesser recommended.

FreeWeb ToolNew
  • Schmertmann Iz
  • C1, C2 corrections
  • Mayne-Poulos I
  • Square / strip / rect
  • Es weighted
  • Lesser recommended
Open Immediate Settle

Underpinning Pier Load

Distribute existing wall or column load over underpinning pits / piers and check soil allowable bearing.

FreeWeb ToolNew
  • Per-pier load
  • Contact pressure
  • q_act vs q_allow
  • Multiple piers
  • OK/NG verdict
  • Persists locally
Open Underpinning

IDF Curve Builder

Talbot or Sherman IDF fit with two-anchor return-period interpolation for any (t, T).

FreeWeb ToolNew
  • Talbot or Sherman
  • 2- vs 25-yr anchors
  • Log-linear T interp
  • Quick lookups
  • 5/30/60/120 min
  • Total depth P
Open IDF Builder

Unit Hydrograph (SCS / Snyder)

Synthetic UH for ungauged watersheds — SCS triangular and Snyder synthetic with peak qp, lag, and base time.

FreeWeb ToolNew
  • SCS triangular
  • Snyder Ct, Cp
  • Peak qp, Tp, Tb
  • Volume check
  • Lag time
  • Method toggle
Open Unit Hydrograph

Reservoir Routing

Modified Puls (Storage-Indication) routing of a triangular inflow through a single-stage reservoir with weir outflow.

FreeWeb ToolNew
  • Triangular inflow
  • Weir outflow
  • Iterative solver
  • Peak Qout, h_peak
  • Attenuation %
  • h_max check
Open Reservoir Routing

Channel Routing (Muskingum)

Route a triangular inflow through a channel reach using Muskingum K, X — outflow peak, attenuation, and stability check.

FreeWeb ToolNew
  • K, X coefficients
  • C0, C1, C2
  • Sum check ≈ 1
  • Peak outflow
  • Attenuation
  • Stability badge
Open Channel Routing

Bridge Scour HEC-18

CSU pier scour and contraction scour per FHWA HEC-18 — Froude, K-factors, ys, and total local scour.

FreeWeb ToolNew
  • CSU pier eq.
  • K1, K2, K3, K4
  • Contraction scour
  • Total scour
  • Froude check
  • Live-bed assumed
Open Bridge Scour

Spread on Pavement

Triangular gutter spread T per HEC-22 §4 — for inlet spacing and curb spread design with Manning n.

FreeWeb ToolNew
  • HEC-22 Eq. 4-2
  • Spread T
  • Curb depth d
  • Velocity
  • T_max check
  • OK/NG verdict
Open Spread on Pavement

Flood Frequency

Estimate T-year peak discharge from sample mean, SD, and skew — Gumbel and simplified Log-Pearson III.

FreeWeb ToolNew
  • Gumbel reduced variate
  • K-T factor
  • LP3 with Cs
  • Inverse normal z(T)
  • Q_T both methods
  • Sample N input
Open Flood Frequency

Pump Station Sizing

Wet-well active volume and cycle-time check (≥ 6 min between starts) per Ten States Standards.

FreeWeb ToolNew
  • Inflow vs pump rate
  • t1 and t2 phases
  • Cycle time
  • V_min recommended
  • Active depth
  • Cycle ≥ 6 min
Open Pump Station

Energy Dissipator (Hydraulic Jump)

Stilling basin hydraulic-jump sizing — sequent depth y2, jump length, energy loss, and USBR basin type.

FreeWeb ToolNew
  • Belanger sequent
  • Froude class
  • Lj ≈ 6·y2
  • Energy loss ΔE
  • USBR Type I-IV
  • Quick design
Open Energy Dissipator

Roundabout Capacity HCM

Single- and two-lane roundabout entry capacity per HCM 2010 (c = A·e^−B·v_c) with V/C and LOS estimate.

FreeWeb ToolNew
  • 4 configurations
  • HCM Eq. 21-1
  • PCE for HV
  • V/C ratio
  • LOS A–F
  • OK/OVER verdict
Open Roundabout

Signalized Intersection LOS

HCM control delay (uniform + incremental + initial-queue) per approach with V/C and LOS A–F.

FreeWeb ToolNew
  • d1 uniform
  • d2 incremental
  • d3 initial queue
  • PF progression
  • Capacity c
  • LOS thresholds
Open Signal LOS

Truck Climbing Lane

AASHTO/DPWH justification — speed reduction ΔV ≥ 15 kph and upgrade truck flow ≥ 200 veh/hr criteria.

FreeWeb ToolNew
  • Speed-reduction approx.
  • Two criteria
  • Truck flow on grade
  • Justified or not
  • Grade %, length L
  • DHV, %T inputs
Open Truck Climbing

Roadway Lighting

Lumen-method roadway lighting — pole spacing for target Eav with CU and LLF, plus poles/km.

FreeWeb ToolNew
  • One-side / opposite / staggered
  • Eav target
  • CU & LLF
  • Pole spacing S
  • Poles per km
  • S/W ratio
Open Roadway Lighting

Crash Rate (RMVM / RMEV)

Segment and intersection crash rate with critical-rate hot-spot test for safety-screening.

FreeWeb ToolNew
  • Segment RMVM
  • Intersection RMEV
  • Critical rate Rc
  • k = 1.645 / 1.96
  • Hot-spot verdict
  • Million-veh exposure
Open Crash Rate

Pavement Marking Quantity

Centerline, edge line, and lane line lengths plus paint volume and reflective bead quantities.

FreeWeb ToolNew
  • Pattern 4-7 / 3-9 / solid
  • Stripe area m²
  • Paint volume L
  • Beads kg
  • Per-line widths
  • Multi-lane support
Open Pavement Marking

PRS92 ↔ WGS84 (Philippines)

Bursa-Wolf 7-parameter coordinate transformation between PRS92 (Clarke 1866) and WGS84/ITRF for legacy-vs-modern survey reconciliation.

FreeWeb ToolNew
  • Both directions
  • Geodetic ↔ ECEF
  • Clarke 1866 / WGS84
  • Editable parameters
  • NAMRIA defaults
  • 9-decimal output
Open PRS92 ↔ WGS84

Contour Interpolation

Linearly interpolate the spot elevation between two contours along a connecting line — for quickly reading topo maps.

FreeWeb ToolNew
  • Spot elevation
  • Slope along line
  • Distance to contours
  • Rise to point
  • Contour interval
  • Persists locally
Open Contour Interp

Prismoidal Volume

Earthwork volume between two cross-sections — Average End-Area and Prismoidal Formula plus the prismoidal correction.

FreeWeb ToolNew
  • AEA: V=L(A1+A2)/2
  • Prism: V=L(A1+4Am+A2)/6
  • Cp correction
  • Mean area
  • m³ output
  • Two-station strip
Open Prismoidal

Closure Adjustment

Distribute traverse misclosure to each leg by Compass (Bowditch) or Transit Rule with relative precision 1:N.

FreeWeb ToolNew
  • Compass / Bowditch
  • Transit Rule
  • Linear misclosure E
  • 1:N precision
  • Per-leg factors
  • Latitude/Departure
Open Closure Adjust

Astronomical Azimuth

Azimuth from sun or Polaris by hour-angle method — using observed φ, δ, and t with East/West correction.

FreeWeb ToolNew
  • Hour-angle method
  • Sun or Polaris
  • N/S declination
  • East / West body
  • 0–360° azimuth
  • Altitude h output
Open Astro Azimuth

Marshall Mix Design

Asphalt mix volumetrics — VTM, VMA, VFA, dust/binder — with DPWH/AASHTO acceptance ranges by layer.

FreeWeb ToolNew
  • Gmm, Gmb, Pb, Gsb
  • VTM 3–5%
  • VMA target by layer
  • VFA range
  • Dust/binder 0.6–1.2
  • PASS/CHECK badge
Open Marshall Mix

Superpave Volumetrics

Mix design at N_design — VTM, VMA, VFA, dust/Pbe, %Gmm at N_initial / N_max with NMAS-based VMA target.

FreeWeb ToolNew
  • VTM target ~4%
  • VMA by NMAS table
  • VFA 65–78%
  • Dust/Pbe 0.6–1.2
  • N_ini ≤ 89%
  • N_max ≤ 98%
Open Superpave

Rebound Hammer → f'c

In-situ concrete strength from Schmidt rebound hammer per ASTM C805 — 10-reading mean, orientation correction, 5%-percentile.

FreeWeb ToolNew
  • 10-reading mean
  • SD & CV
  • Orientation correction
  • 3 strength curves
  • 5%-percentile
  • ACI 214.4
Open Rebound→f'c

Concrete Core Strength (ASTM C42)

Correct cored cylinder strength to standard cylinder — L/D, diameter, moisture conditioning, and casting-axis factors.

FreeWeb ToolNew
  • L/D table
  • Diameter factor
  • Soaked / air / as-rec.
  • Axis perp / parallel
  • Combined K
  • fc,std MPa
Open Core Strength

Aggregate Gradation & FM

Sieve analysis with % passing curve, fineness modulus, classification, and ASTM C33 fine-aggregate envelope check.

FreeWeb ToolNew
  • 9 sieve sizes
  • % passing live
  • Fineness Modulus FM
  • Classification
  • C33 envelope
  • OK/CHECK badge
Open Gradation

Earned Value Management

Full EVM dashboard from PV, EV, AC, BAC — CPI, SPI, CV, SV, EAC, ETC, VAC, TCPI per PMBOK.

FreeWeb ToolNew
  • 3 EAC methods
  • CPI, SPI
  • CV, SV with sign
  • VAC, TCPI
  • ON TRACK badge
  • Persists locally
Open EVM

PERT 3-Point Estimate

Beta-distribution TE = (O+4M+P)/6 with σ, variance, triangular alternative, and confidence range.

FreeWeb ToolNew
  • Beta TE
  • σ & variance
  • Triangular TT
  • k·σ confidence
  • O / M / P inputs
  • Standard 95% z=1.96
Open PERT

Resource Histogram & Leveling

List up to 8 activities with start/finish/resources — peak demand, overload days vs cap, and total resource-days.

FreeWeb ToolNew
  • Up to 8 activities
  • Daily total
  • Peak day
  • Overload count
  • Avg demand
  • Cap check
Open Resource Hist.

Cost Escalation Index

Escalate base-year cost to a target year using a price index — escalation factor, total %, and CAGR.

FreeWeb ToolNew
  • DPWH CCPI / ENR CCI
  • Escalation factor
  • Total escalation %
  • Years gap
  • CAGR % / yr
  • ₱-formatted
Open Cost Escalation

Bid Evaluation Matrix

Compare up to 6 bidders by total bid vs ABC, with post-qualification scoring per RA 9184 / GPPB rules.

FreeWeb ToolNew
  • ABC ceiling check
  • Sort lowest first
  • PQ score min
  • Lowest responsive
  • Rejected count
  • AWARDED badge
Open Bid Eval

Material Take-Off

Concrete, formwork, and rebar take-off for a single rectangular RC element with unit-cost rollup to ₱.

FreeWeb ToolNew
  • Conc., form, rebar
  • Main + stirrup wt
  • Waste %
  • Unit costs
  • Total ₱
  • Per-element MTO
Open MTO

Equipment O&O Cost

Heavy-equipment owning + operating cost per hour per Caterpillar PHB — depreciation, interest, fuel, FOG, repair, tires.

FreeWeb ToolNew
  • Depreciation
  • Interest + tax
  • Fuel + FOG
  • Repair factor
  • Tires/hr
  • Total ₱/hr
Open Equipment Cost

HVAC Cooling Load (CLTD)

Sensible and latent cooling load using ASHRAE CLTD/SCL/CLF — roof, walls, glass, lights, people, equipment.

FreeWeb ToolNew
  • U·A·CLTD components
  • Glass solar SC·SHGF
  • People sens + lat
  • Lights & equip CLF
  • kW + TR output
  • Total inc. latent
Open HVAC Load

Duct Sizing (Equal-Friction)

ASHRAE equal-friction sizing — round D, velocity, equivalent rectangular a × b at target Δp/L.

FreeWeb ToolNew
  • m³/hr input
  • Pa/m target
  • Round D mm
  • Velocity m/s
  • Rect a × b
  • Reynolds Re
Open Duct Sizing

Cable Sizing & VD (PEC)

Pick a copper THWN/THHN size for ampacity and voltage drop ≤ target per PEC 2017 / NEC.

FreeWeb ToolNew
  • 1-ph & 3-ph
  • 60/75/90 °C
  • Continuous 1.25 ×
  • Derating
  • VD < 3% target
  • Final size mm²
Open Cable Sizing

Lightning Protection

Rolling-sphere zone of protection and a simplified IEC 62305 risk index — recommends LPL I–IV.

FreeWeb ToolNew
  • R per LPL
  • Rolling-sphere r
  • IEC Ad area
  • Strikes/yr Nd
  • C2-C5 factors
  • OK/UPGRADE
Open Lightning Prot.

Lumen Method Lighting

Indoor lumen-method design — fixture count for a target Eav given CU, LLF, RCR, and lamp lumens.

FreeWeb ToolNew
  • RCR auto
  • LLF = BF·LLD·LDD·RSDD
  • N (calc and integer)
  • Resulting Eav
  • Lamps/fixture
  • Workplane height
Open Lumen Method

Septic Tank / STP Sizing

Three-compartment septic tank sizing per DENR DAO 2019-19 — wastewater volume, sludge, and dimensions.

FreeWeb ToolNew
  • Daily Q
  • Liquid Vl
  • Sludge Vs
  • Total Vt
  • W × L recommended
  • 3-4 compartments
Open Septic Sizing

Stormwater BMP Sizing

Bioretention cell or dry detention basin from drainage area and runoff coefficient — WQV, area, and infiltration time.

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  • Bio & detention
  • Water Quality Vol.
  • Required area
  • Drain time
  • Soil k input
  • Drain target check
Open Stormwater BMP

RUSLE Soil Erosion

Annual soil loss A = R·K·LS·C·P from RUSLE — gives soil loss vs tolerable T for ESC plan design.

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  • R, K, LS, C, P
  • McCool LS
  • t/ha/yr output
  • Total area loss
  • T tolerable check
  • Control needed badge
Open RUSLE

WWTP Per-Capita Sizing

Activated-sludge sizing from population equivalent — Q_avg, peak Q, BOD/TSS, and aeration-tank volume V.

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  • Q_avg + peak factor
  • BOD & TSS loads
  • F/M ratio
  • MLSS
  • Aeration V
  • HRT hr
Open WWTP Sizing

Empirical Period Ta (NSCP / ASCE 7)

Approximate fundamental period Ta = Ct · hn^x with Cu upper limit per NSCP / ASCE 7 §12.8.2.

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  • 7 system types
  • Ct, x lookup
  • Ta in seconds
  • Cu by SD1
  • T_max for V_min
  • Method A
Open Period Ta

Floor Vibration (AISC DG-11)

Walking-excitation peak acceleration ap/g vs occupancy limits per AISC Design Guide 11 (offices, residential, dining, rhythmic).

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  • fn, β, W inputs
  • P0 = 0.29 kN walking
  • 5 occupancy limits
  • ap/g % g
  • PASS/FAIL badge
  • DG-11 Eq. 4.1
Open Floor Vibration

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