Engineering Calculators
Unit converters and equation solvers for working engineers.
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ToolGear Generator (3D)Design a spur gear in 3D & export STEP/STLToolSection Properties CalculatorArea, moment of inertia & section modulusCalculatorShelf Sag (Deflection)δ = 5WL³ / (32 E b h³)ToolISO Fits & Tolerances CalculatorHole/shaft limits & clearance (H7/g6)ToolConduit Fill CalculatorHow many wires fit — NEC Chapter 9 fillReferenceAlt Codes for Symbols63-row reference tableToolHexagonal Packing CalculatorStaggered grid spacing, coordinates & container fitToolPress-Fit / Interference-Fit CalculatorContact pressure, holding torque & shrink-fit temperatureToolBeam CalculatorShear & bending moment diagramsToolGeneva Mechanism CalculatorIndex angle, dwell, peak speed, acceleration & torqueToolVibration Isolation CalculatorNatural frequency, transmissibility & mount sizingToolShaft Design CalculatorBending + torsion stress & safety factor
Build & simulate in your browser
3D CAD3D ModelerBuild a solid part from primitives and booleans in your browser, then export STEP or STL.Open the tool ›Configurator3D Part StudioTune a parametric part — gear, knob, bracket, plate — with sliders and export STEP or STL.Open the tool ›SimulatorThroughput Factory SimRun a production line and beat the bottleneck — a Theory‑of‑Constraints strategy game.Open the tool ›GeneratorCam Profile GeneratorDesign follower motion and export a ready‑to‑cut cam profile as DXF.Open the tool ›3DGear GeneratorModel an involute spur gear in 3D and export STEP or STL for printing or CNC.Open the tool ›InteractiveTruss AnalyzerSolve every member force in a truss and export the frame as DXF.Open the tool ›InteractiveBeam CalculatorDraw live shear and bending‑moment diagrams for any supported beam and loads.Open the tool ›
How-To Guides
GuideHow to Design a Bolted JointFrom bolt pattern to tightening torqueGuideHow to Check a Fillet WeldPeak force → throat stress → fillet size → base metalGuideHow to Balance a Rotor & Isolate Its VibrationSpeed² force → isolation → bearing life → materialGuideHow to Size a Pump for a Piping SystemFluid properties → head → power → motorGuideHow to Find Pipe Friction and Pressure DropReynolds number → friction factor → head lossGuideHow to Size a Drainage Channel or CulvertDesign flow → channel shape → normal depth → velocity & regimeGuideHow to Size a Ventilation FanAirflow → duct → system pressure → power → motorGuideHow to Design a ShaftFrom bending loads to diameter, fits & materialGuideHow to Mount a Gear, Pulley or Bearing on a ShaftTorque → key / spline / press-fit → bearing life → materialGuideHow to Choose a Fit (Clearance, Transition or Interference)What the joint does → clearance / transition / interference → grade & basis → stack-upGuideHow to Design an O-Ring Seal (Groove / Gland)What it seals → cross-section & AS568 size → squeeze → gland fill → stretch & gap → tolerancesGuideHow to Select a Rolling BearingLoads & duty → equivalent load P → L10 life → reliability → mount itGuideHow to Design a GearboxRatio → teeth → shaft → bearing → modelGuideHow to Convert Rotary MotionPick the mechanism for the output motion you needGuideHow to Design a Rotary Indexing DriveIndex count → dwell → torque → motorGuideHow to Set Up a Sheet-Metal BendFlat pattern → die & radius → tonnage → punched holesGuideHow to Check a Part for FatigueFrom cyclic load to safe infinite or finite lifeGuideHow to Design a Compression SpringRate & geometry → coil stress → buckling & surge → fatigue lifeGuideHow to Choose the Right SpringPush, pull, twist or hold — pick the spring type and how each one failsGuideHow to Check a Column for BucklingFrom cross-section to critical load, slenderness & materialGuideHow to Read a Stress-Strain CurveFrom the tensile test to modulus, yield, strength & toughnessGuideHow to Size a Belt or Chain DriveFrom speed ratio to pulleys, sprockets, length & motorGuideHow to Select and Size a BeamLoads → moment → section → deflectionGuideHow to Design a BracketLoad & offset → bending → section → bolt or weld group → deflectionGuideHow to Build a Retaining WallHeight & soil → overturning & sliding check → base → drainage → materialsGuideHow to Plan a LiftCentre of gravity → sling angle → spreader bar → hardwareGuideHow to Design a Pressure VesselShell wall → heads → material → bolted closureGuideHow to Analyze a TrussMember forces → critical members → size the sections → materialGuideHow to Dial In Speeds & Feeds for a Milling JobCutting speed → RPM → feed → MRR → powerGuideHow to Measure a Screw ThreadTarget pitch diameter → three-wire method → best wire size → fit classGuideUnderstanding Gage R&R (Measurement System Analysis)What MSA is → set up the study → read %GRR & ndc → fix a bad gaugeGuideHow to Run a Process Capability StudyTrust the gauge → prove the process is stable → measure Cp & Cpk → tie it to the toleranceGuideHow to Compare Two Processes (Is the Difference Real?)Plan the sample size → run a two-sample t-test → report the real differenceGuideHow to Build a BookcaseShelf span → hole layout → joinery → wood movementGuideHow to Build a French Cleat WallDesign the cleat → cut the plywood → check the load → build the holdersGuideHow to Scale and Cook a RecipeScale the batch → weigh it out → dial in the dough → set the oven → cook to temperatureGuideHow to Design a Simple Electronic CircuitOhm’s law → LED resistor → read the markings → add timing & filteringGuideHow to Size and Wire a CircuitLoad current → wire gauge → voltage drop → conduit fillGuideHow to Size a Motor Branch CircuitFull-load current → conductor → protection → overload → voltage dropGuideHow to Design a Filter CircuitFirst-order RC cutoff → buffer & amplify → LC resonance → real component valuesGuideHow to Knit or Crochet a Garment That FitsSwatch → measure gauge → stitch count → needle sizeGuideHow to Estimate Building Heat LossFabric loss → ventilation → heating plant → distributionGuideHow to Lay Out a Fabricated PartSolve the triangles → divide the circle → hole coordinates → set out the curvesGuideHow to Design a Part for 3D PrintingModel the solid → pick a material → cost the print → design in the fitsGuideHow to Balance a Production LineTakt → time study → balance → learning curve → OEEGuideHow to Design a Power Screw (Lead Screw) DriveLoad → torque, self-locking, buckling & thrust bearingGuideHow to Insulate a PipeSet the target → bare-pipe loss → size the lagging → stop the sweat → allow for movementGuideHow to Design a CamTiming diagram → motion law → base circle & pressure angle → no undercut → contact & materialGuideHow to Account for Wood MovementWhich way it moves → how much (EMC swing) → let panels float → fasten across the grain → when sheet goods let you ignore itGuideHow to Gauge a TankPin the shape → account for the heads → depth→volume → strap chart → work backwards & convertGuideHow to Calculate Section PropertiesFind the centroid → moment of inertia → section modulus & radius of gyration → build up a composite → put them to workGuideHow to Design a Spur GearSet the ratio & tooth counts → fix module & pressure angle → shape the involute tooth → check bending & pitting → generate, print or cutGuideHow to Set Up and Check a Taper or AngleRead the callout → set it on a sine bar → cut it → hold the tolerance
Cheat Sheets
Cheat SheetMechanics & Motion FormulasKinematics, Newton’s laws, energy, momentum & rotationCheat SheetHeat Transfer Formulas & DataConduction, convection, radiation, thermal resistance, k & h valuesCheat SheetBeam Deflection & Bending FormulasReactions, max moment & deflection for the common casesCheat SheetArea Moment of Inertia & Section PropertiesI, S, r and J for the standard cross-sectionsCheat SheetBolt Torque, Preload & GradesK-factors, proof strengths and stress areasCheat SheetISO Fits & TolerancesThe common hole-basis fits, what they do and when to use themCheat SheetFillet Weld Sizing & SymbolsThroat, allowable stress, minimum sizes and the 1.392 ruleCheat SheetSpur Gear Formulas & Tooth ProportionsModule, pitch diameter, tooth sizes, ratio & centre distanceCheat SheetTap & Clearance Drill SizesMetric & unified tap drills and clearance holesCheat SheetGD&T Symbols Quick ReferenceThe 14 characteristics, modifiers & the feature control frameCheat SheetSI Units, Prefixes & ConversionsBase units, the prefix ladder and the conversions you actually useCheat SheetOhm’s Law & Electrical FormulasThe power wheel, series/parallel and AC powerCheat SheetPipe Flow & Reynolds NumberFlow regimes, head loss and the numbers to knowCheat SheetSPC & Process Capability Cheat SheetControl-chart constants, limits and Cp/CpkCheat SheetLean & Industrial-Engineering MetricsTakt time, OEE, Little’s law, line balancing, EOQ & work measurementCheat SheetMaterials Properties & SelectionDensity, stiffness, strength, thermal data & the Ashby selection indices
Mechanics & Motion
ToolFour-Bar Linkage SimulatorAnimate the mechanism & trace the coupler curveToolSlider-Crank SimulatorAnimate the piston engine & get its motionToolScotch Yoke SimulatorAnimate the slotted yoke & get the SHM motionToolQuick-Return Mechanism SimulatorAnimate the crank-shaper & get the time ratioToolToggle / Knuckle-Joint Press CalculatorTurn a small push into a huge clamping forceToolCam Profile GeneratorDesign follower motion & export the profile (DXF)ToolGeneva Mechanism CalculatorIndex angle, dwell, peak speed, acceleration & torqueToolUniversal Joint SimulatorHooke’s / Cardan joint velocity rippleToolProjectile Motion CalculatorRange, max height, flight time & impact + animated arcToolSimple Pendulum CalculatorPeriod, frequency & the large-amplitude correction + animated swingToolInclined Plane / Ramp Friction CalculatorWill it hold or slide? Angle of repose & push forceToolCapstan / Belt-Friction CalculatorHold force, wraps & the e^(μβ) ruleConverterSpeedConverterAccelerationConverterTimeConverterFrequencyCalculatorVelocityv=Δx/tCalculatorAccelerationa=Δv/tCalculatorFinal Velocity (constant acceleration)v = v0 + a·tCalculatorDisplacement (constant acceleration)x = v0t + ½a·t2CalculatorVelocity from Displacement (constant acceleration)v2 = v02 + 2a·xCalculatorWave Speedv=fλCalculatorCentripetal Accelerationa=v2/rCalculatorPendulum PeriodT=2π√(L/g)Calculatorde Broglie Wavelengthλ=h/pCalculatorAngular Velocityω=v/rCalculatorAngular Accelerationα=Δω/tCalculatorPeriod & FrequencyT=1/fCalculatorAngular Frequencyω=2πfCalculatorWavenumberk=2π/λ
Forces & Structures
ToolTruss AnalyzerMember forces, tension/compression & DXF exportToolBeam CalculatorShear & bending moment diagramsToolMohr’s Circle CalculatorPrincipal stresses & stress transformationToolSection Properties CalculatorArea, moment of inertia & section modulusToolBuilt-Up Section Properties CalculatorComposite centroid, moment of inertia & principal axesToolColumn Buckling CalculatorEuler critical load, slenderness & mode shapeToolPressure Vessel Stress CalculatorHoop & longitudinal stress, Lamé & wall thicknessToolFlat Plate Deflection & Stress CalculatorCircular & rectangular plate under uniform pressureToolFatigue / Goodman Diagram CalculatorConstant-life diagram & factor of safetyToolS-N Curve / Fatigue-Life EstimatorWöhler curve & cycles to failureToolNotch Sensitivity / Fatigue Factor Kf Calculatorq & Kf = 1 + q(Kt−1) from KtToolStress Concentration Factor Calculator (Kt)Geometric Kt from a shoulder fillet or hole (Peterson)ToolEndurance Limit Calculator (Marin Factors)Corrected Se from Sut — kakbkckdkeToolSling Angle & Leg Tension CalculatorLoad-angle factor 1/sinθ & tension per legToolTwo-Point Lift Load Share CalculatorLoad on each pick from the centre of gravityToolTrailer Tongue Weight & Axle Load CalculatorTongue weight, axle load & the 10–15% bandToolFloating Shelf Load Capacity CalculatorBracket pull-out & how much a shelf holdsToolLever & Seesaw Balance CalculatorMoment balance: which way it tips & the balance pointToolLadder Safe Angle CalculatorWill the feet slip? Safe lean angle & the 4-to-1 ruleToolForklift Load Capacity CalculatorLoad-centre derating, capacity & tip-over marginToolRetaining Wall CalculatorOverturning & sliding stability from earth pressureConverterMassConverterDensityConverterForceConverterPressureConverterTorqueConverterSpecific VolumeCalculatorForceF=maCalculatorFriction ForceF=μNCalculatorPressurep=F/ACalculatorDensityρ=m/VCalculatorStressσ=EεCalculatorHooke's LawF=kxCalculatorWeightW=mgCalculatorMomentump=mvCalculatorNewton’s GravitationF=Gm1m2/r2CalculatorTorqueτ=rFCalculatorAngular MomentumL=IωCalculatorRotational Newton's Second Lawτ=IαCalculatorEscape Velocityv=√(2GM/r)CalculatorCentripetal ForceF=mv2/rCalculatorGravitational Field Strengthg=GM/r2CalculatorImpulseJ=FΔtCalculatorEngineering Strainε=ΔL/LCalculatorMoment of Inertia (Point Mass)I=mr2CalculatorKepler's Third LawT2=4π2a3/GMCalculatorMoment of Inertia (Solid Disk)I=½mr2CalculatorHoop Stress (Thin-Walled)σ=PD/2tCalculatorShear Stressτ=F/ACalculatorBending Stressσ=My/ICalculatorTorsional Shear Stressτ=Tr/JCalculatorSecond Moment of Area (Rectangle)I=bh³/12CalculatorPolar Moment of Area (Solid Shaft)J=πd⁴/32CalculatorSection ModulusZ=I/cReferenceMetric Tap Drill Chart14-row reference tableReferenceInch Tap Drill Chart (UNC / UNF)39-row reference tableReferenceMetric Thread Dimensions Chart14-row reference tableReferenceInch Thread Dimensions Chart (UNC / UNF)39-row reference tableReferenceMetric Bolt & Nut Wrench Size Chart25-row reference tableReferenceInch / SAE Bolt & Nut Wrench Size Chart14-row reference tableReferenceMetric Socket-Head Cap Screw Counterbore Chart11-row reference tableReferenceMetric Bolt Torque Chart13-row reference tableReferenceInch / SAE Bolt Torque Chart12-row reference table
Machine Design
ToolVibration Isolation CalculatorNatural frequency, transmissibility & mount sizingToolShaft Design CalculatorBending + torsion stress & safety factorToolShaft Torsion Calculator (Angle of Twist)Angle of twist, shear stress & torsional stiffnessToolShaft Critical Speed Calculator (Whirling Speed)First critical / whirling speed — rotor + self-weightToolBolt Torque CalculatorTightening torque & preload (T = K·F·d)ToolBolted Joint CalculatorStiffness, load sharing, separation & bolt fatigueToolBolt Circle CalculatorHole X/Y coordinate generator (PCD)ToolPin / Clevis Shear CalculatorDouble shear, bearing & pin bending with factor of safetyToolHexagonal Packing CalculatorStaggered grid spacing, coordinates & container fitToolBolt Group Shear CalculatorEccentric load: force on each bolt + critical boltToolWeld Group Shear CalculatorEccentric load: peak force per unit length + fillet sizeToolFillet Weld Strength CalculatorAllowable / design load & required leg sizeToolISO Fits & Tolerances CalculatorHole/shaft limits & clearance (H7/g6)ToolISO 2768 General Tolerances CalculatorTitle-block linear, angular & chamfer tolerancesToolPress-Fit / Interference-Fit CalculatorContact pressure, holding torque & shrink-fit temperatureToolO-Ring Gland / Groove Design CalculatorSqueeze, gland fill & stretch for a sealing grooveToolHydraulic Cylinder CalculatorExtend & retract force, speed & volumeToolPneumatic Valve Sizing CalculatorCv for multiple cylinders + schematicToolGear Ratio CalculatorSpeed, torque & animated gear trainToolGear Tooth Bending Stress CalculatorLewis stress, velocity factor & safety factorToolGear Contact Stress CalculatorSurface durability / pitting, Hertz & AGMAToolPlanetary Gear CalculatorEpicyclic ratio, torque split & animationToolGear Generator (3D)Design a spur gear in 3D & export STEP/STLToolGear Rack Generator (3D)Design a spur or helical involute gear rack in 3D & export STEP/STLToolSprocket Generator (3D)Design a roller-chain sprocket in 3D & export STEP/STL/DXF/SVGToolTiming-Belt Pulley Generator (3D)Design a GT2 / HTD / MXL / XL pulley in 3D & export STEP/STLTool3D Modeler (CAD)Build a solid from primitives & booleans — export STEP/STLTool3D Part Studio (Configurator)Tune a parametric part with sliders — export STEP/STLToolCompression Spring CalculatorRate, force, stress & animated coilToolExtension Spring CalculatorRate, initial tension & hook stressToolTorsion Spring CalculatorRate, wind-up angle & bending stressToolBelleville (Disc) Spring CalculatorLoad, rate, DIN 2093 stress & stacksToolBelt & Pulley CalculatorRatio, belt speed, length & animationToolBelt Conveyor CalculatorCapacity (t/h & m³/h) & drive powerToolChain & Sprocket CalculatorRatio, chain length, centre distance & speedToolWorm Gear CalculatorRatio, lead angle, efficiency & self-lockingToolBevel Gear CalculatorRatio, pitch angles, virtual teeth & tooth forcesToolLead Screw / Power Screw CalculatorRaise/lower torque, efficiency & self-lockingToolSet Screw Holding Power CalculatorSeating torque, holding power & torque capacityToolRetaining Ring Thrust Load CalculatorGroove deformation & ring-shear thrust capacityToolKeyway / Parallel Key Sizing CalculatorShaft key shear & bearing stress + cross-sectionToolThread Engagement & Strip-Out CalculatorEngagement length so the bolt breaks before the threads stripToolInvolute Spline Torque Capacity CalculatorTooth shear & flank bearing stress, torque capacityToolBearing Life Calculator (L10)ISO 281 rating life, hours & required ratingToolHertzian Contact Stress CalculatorContact pressure & patch size for balls, rollers & racesToolSnap-Fit Calculator (Cantilever Snap Joint)Assembly strain & push-on / pull-off force for a snap hookToolFlywheel Energy & Burst-Speed CalculatorEnergy stored, rim stress & burst speedCalculatorCylinder Piston Speedv=4Q/(πD2)CalculatorShaft PowerP=τωCalculatorShaft Power from RPMP=τNπ/30CalculatorMechanical Efficiencyη=Pout/PinCalculatorHydraulic / Pneumatic PowerP=QΔPCalculatorPipe Pressure Drop (Darcy–Weisbach)ΔP=f(L/D)ρv2/2CalculatorOrifice / Valve Flow RateQ=CdA√(2ΔP/ρ)CalculatorLead Screw Drive TorqueT=F·lead/(2πη)CalculatorBolt Tightening Torque & PreloadT=K·d·FCalculatorBelt / Gear Peripheral Speedv=πDN/60CalculatorPump Hydraulic PowerP=ρgQHCalculatorPump Brake (Shaft) PowerP=ρgQH/ηCalculatorFan / Blower PowerP=QΔp/ηReferenceISO Tolerance Grades (IT) Chart13-row reference table
Manufacturing
ToolFeeds & Speeds CalculatorSpindle RPM, feed rate & MRRToolCutting Power & Torque CalculatorSpindle power (kW/hp) & torque from MRRToolTap Drill & Thread Size CalculatorTap-drill Ø, thread engagement % & pitch diameterToolTaper CalculatorTaper per foot, angle, ratio & end diametersToolSine Bar CalculatorGauge-block stack height & angle settingToolThree-Wire Thread Measurement CalculatorMeasurement over wires & best wire sizeToolPress-Brake Bending Force CalculatorAir-bend tonnage, die opening & inside radiusToolGD&T Symbol Reference & Frame DecoderAll 14 symbols + a live feature-control-frame builderToolWelding Symbol Chart & BuilderAWS A2.4 weld symbols + a live symbol builderToolTrue Position Calculator (GD&T)Actual position, MMC/LMC bonus tolerance & pass/failToolGO / NO-GO Gauge CalculatorPlug & ring gauge tolerances by the 10% rule with wear allowanceToolTolerance Stack-Up CalculatorWorst-case & statistical (RSS) gap + CpkToolGage R&R Calculator (MSA)Repeatability, reproducibility, %GRR & ndcToolOEE CalculatorAvailability × Performance × Quality & the loss waterfallToolBend Allowance CalculatorSheet-metal flat pattern, BA, BD & setbackToolSurface Finish ConverterRa ↔ RMS ↔ µm/µin ↔ ISO N-gradeToolPunch / Blanking Force CalculatorPress tonnage to punch a hole — perimeter × thickness × shearCalculatorSpindle Speed from Cutting SpeedN=Vc/(πD)CalculatorMilling Table Feed RateVf=N·fz·zCalculatorMaterial Removal Rate (Milling)MRR=ap·ae·VfCalculatorTurning Surface Finish (Ra)Ra=f²/(32r)CalculatorTurning / Machining Timet=L/(f·N)ReferenceDrill Size Decimal Equivalents Chart138-row reference tableReferenceSheet Metal Gauge Thickness & Weight Chart28-row reference tableReferenceCutting Speed Chart (SFM) by Material16-row reference tableReferenceSurface Finish Chart — Ra Roughness Grades12-row reference table
Industrial Engineering
ToolEOQ Calculator (Economic Order Quantity)Optimal order size, reorder point & the cost curveToolTakt Time CalculatorTakt time, required rate, operators needed & a capacity checkToolLine Balancing CalculatorTakt time, fewest stations, efficiency & balance delayToolLearning Curve CalculatorCost & time for a production run (Wright & Crawford)ToolQueue / Waiting-Line CalculatorWait time, utilisation & how many servers you needToolStandard Time / Time Study CalculatorNormal & standard time, output rate & labour cost from a stopwatch studyToolRequired Number of Observations (Time-Study Sample Size)How many stopwatch cycles you need for a target precisionCalculatorLittle's Law (WIP, Throughput & Lead Time)WIP = TH · CTCalculatorTakt Time (pace to customer demand)Takt = Available Time / DemandCalculatorAssembly-Line Balancing EfficiencyE = ΣT / (N · C)CalculatorCapacity / Resource Utilization (ρ = λ/μ)ρ = Demand Rate / Capacity Rate
Statistics
ToolSample Size CalculatorMargin of error, confidence level & the normal curveToolConfidence Interval CalculatorMean (Student-t) & proportion (Wilson) intervalsToolTwo-Sample t-Test CalculatorCompare two group means — Welch & pooledToolLinear Regression CalculatorLeast-squares line, R², slope test & predictionToolProcess Capability Calculator (Cp, Cpk)Cp, Cpk, Pp, Ppk & expected out-of-spec ppmToolControl Chart Calculator (X̄-R, I-MR)Control limits, sigma & out-of-control rulesToolAcceptance Sampling Plan CalculatorOC curve, producer & consumer risk (AQL / LTPD)ToolAttribute Control Chart Calculator (p, np, c, u)p, np, c & u charts with control limits & out-of-control rules
Materials
ToolStress–Strain Curve ExplorerBuild the tensile-test diagram from datasheet valuesToolHardness ConverterVickers ↔ Brinell ↔ Rockwell (+ tensile)ToolMetal Weight CalculatorBar, plate, tube, hex & angle — weight, per length & costToolWeld Metal / Deposition Weight CalculatorFillet & groove welds — deposit weight, filler to buy & costToolCoil / Sheet Run-Length & Weight CalculatorStrip & sheet coils — length ↔ weight ↔ outside diameterToolMaterials DatabaseSearch, chart & compare material propertiesReferenceShore Durometer Hardness Chart9-row reference table
Fluids
ToolReynolds Number CalculatorFlow regime: laminar, transitional or turbulentToolPipe Pressure Drop CalculatorDarcy–Weisbach head loss, Δp & pumping powerToolMoody Chart CalculatorDarcy friction factor f from Re & roughness ε/DToolBernoulli Equation CalculatorPressure, velocity & elevation head — solve for any oneToolOpen-Channel Flow Calculator (Manning)Discharge, velocity, normal depth & Froude numberToolPump Power & Affinity Law CalculatorHydraulic, shaft & motor power; speed/impeller scalingToolFan Power & Sizing CalculatorAir & brake power (BHP), affinity laws & altitude/temperature derateToolTotal Dynamic Head CalculatorPump head: static + pressure + frictionToolNPSH Calculator (Cavitation)NPSH available vs required — will the pump cavitate?ToolDrag Force & Terminal Velocity CalculatorDrag force, dynamic pressure, power & terminal velocityToolFluid Properties DatabaseDensity, viscosity & heat properties vs temperatureConverterMass FlowConverterVolume FlowConverterDynamic ViscosityConverterKinematic ViscosityConverterSurface TensionCalculatorReynolds NumberRe=ρVD/μCalculatorVolumetric Flow RateQ=AVCalculatorHydrostatic PressureP=ρghCalculatorDrag ForceF=½ρv2CdACalculatorHagen–Poiseuille FlowQ=πr4ΔP/8μLCalculatorHazen–Williams Head Loss (Water Pipe Friction)hf = 10.67·L·Q1.852 / (C1.852D4.8704)CalculatorMinor Loss (Fittings, Valves & Bends)hL = K·V2 / 2gCalculatorControl Valve Sizing — Flow Coefficient (Cv)Cv = Q√(SG/ΔP)CalculatorBuoyant ForceF=ρgVCalculatorYoung–Laplace PressureΔP=2γ/rCalculatorMass Flow Rateṁ=ρAvCalculatorCapillary Rise (Jurin)h=2γ/ρgrCalculatorPrandtl NumberPr=μcp/kCalculatorMach NumberMa=v/cCalculatorHydraulic RadiusRh=A/PCalculatorWeber NumberWe=ρv²L/γCalculatorFroude NumberFr=v/√(gL)CalculatorPéclet NumberPe=vL/αCalculatorSpecific Weightγ=ρgCalculatorSpeed of Sound in a Gasc=√(γRT/M)CalculatorGrashof NumberGr=gβΔT L³/ν²CalculatorPump / Fan Affinity Law — FlowQ2/Q1=N2/N1CalculatorPump / Fan Affinity Law — Head / PressureH2/H1=(N2/N1)2CalculatorPump / Fan Affinity Law — PowerP2/P1=(N2/N1)3CalculatorSchmidt NumberSc=ν/DCalculatorStrouhal NumberSt=fL/vCalculatorKnudsen NumberKn=λ/LCalculatorCapillary NumberCa=μv/γCalculatorBond (Eötvös) NumberBo=ρgL²/γReferenceNPS Pipe Schedule Chart18-row reference table
Heat & Energy
ToolComposite Wall R-Value CalculatorR-value, U-value & heat loss + temperature profileToolHeat Exchanger Calculator (LMTD)Heat duty, area, LMTD, effectiveness & NTUToolSaturated Steam Property CalculatorInterpolate the steam table by T, P or quality xToolPipe Heat Loss & Insulation CalculatorHeat loss per metre, surface temp & lagging thicknessToolHeat Sink & Junction Temperature CalculatorJunction temp Tj & the heat sink you need, from θjc/θcs/θsaToolThermal Expansion & Stress CalculatorGrowth ΔL = αLΔT & restrained stressToolPsychrometric CalculatorMoist-air properties & live psychrometric chartToolHVAC Duct Sizing CalculatorSize a round or rectangular duct for a given airflowConverterEnergyConverterPowerConverterTemperatureConverterThermal ConductivityConverterSpecific HeatConverterHeat Transfer CoefficientConverterHeat Flux (Irradiance)ConverterSpecific Energy (Calorific Value)ConverterVolumetric Energy DensityConverterThermal ResistanceCalculatorPotential EnergyPE=mghCalculatorKinetic EnergyKE=½mv2CalculatorIdeal Gas LawPV=nRTCalculatorSensible HeatQ=mcΔTCalculatorLatent HeatQ=mLCalculatorThermal Efficiencyη=W/QCalculatorStefan–Boltzmann Lawj=σT4CalculatorWien's Displacement LawλmaxT=bCalculatorIdeal Gas Densityρ=PM/RTCalculatorHeat Conduction RateQ=kAΔT/LCalculatorConvective Heat Transfer RateQ=hAΔTCalculatorMass–Energy EquivalenceE=mc2CalculatorPhoton EnergyE=hfCalculatorMechanical PowerP=FvCalculatorRotational Kinetic EnergyE=½Iω2CalculatorElastic Potential EnergyE=½kx2CalculatorGravitational Potential EnergyU=GMm/rCalculatorLinear Thermal ExpansionΔL=αLΔTCalculatorRMS Molecular Speedv=√(3kBT/m)CalculatorElectrical EnergyE=PtCalculatorConductive Thermal ResistanceR=L/kACalculatorHeat Fluxq=Q/ACalculatorBiot NumberBi=hL/kCalculatorThermal Diffusivityα=k/ρcpCalculatorNusselt NumberNu=hL/kCalculatorStanton NumberSt=h/(ρv c_p)CalculatorVolumetric Thermal ExpansionΔV=βVΔTCalculatorLewis NumberLe=α/DCalculatorEckert NumberEc=v²/(c_pΔT)ReferenceSaturated Steam Table (Water) — by Temperature45-row reference tableReferenceSaturated Steam Table (Water) — by Pressure50-row reference table
Electrical & Electronics
ToolOhm’s Law CalculatorAny two of V, I, R, P → the other twoToolVoltage Drop CalculatorWire sizing: volts dropped & % over a runToolWire Ampacity & Gauge CalculatorAWG size for a load — NEC 310.16 + deratingToolGround Wire Size CalculatorEGC & GEC — NEC 250.122 & 250.66ToolMotor Circuit SizerWire, breaker/fuse & overload — NEC Article 430ToolDwelling Load CalculatorResidential service & feeder size — NEC 220 & 220.82ToolConduit Fill CalculatorHow many wires fit — NEC Chapter 9 fillToolConduit Bending CalculatorOffsets, saddles & 90° stubs — where to mark and bendToolBox Fill CalculatorHow many wires fit in a box — NEC 314.16ToolResistor Colour Code CalculatorDecode 4/5/6 bands ↔ resistanceToolCapacitor Code CalculatorDecode 104 / 4n7 ↔ capacitanceToolLED Resistor CalculatorSeries current-limiting resistor for an LEDTool555 Timer CalculatorAstable frequency & monostable pulse widthToolRC Filter CalculatorLow-pass/high-pass cutoff & Bode plotToolOp-Amp Gain CalculatorInverting, non-inverting, buffer & difference gainToolLC / RLC Resonant Frequency CalculatorResonant frequency, Q & bandwidth — series or parallelToolStrain Gauge & Wheatstone Bridge CalculatorBridge output ↔ strain ↔ stress (quarter/half/full)ToolThermocouple Calculator (Type K, J, T, E, N, R, S, B)mV ↔ temperature with cold-junction compensationToolThree-Phase Power CalculatorkW, kVAR, kVA, power factor & capacitor sizingToolMotor Full-Load Current CalculatorFLA, kVA & starting (inrush) currentToolTransformer CalculatorkVA → amps, turns ratio & fault currentToolPCB Trace Width CalculatorCopper width for a current & temp rise (IPC-2221)ToolSchematic BuilderDraw electrical, pneumatic & hydraulic schematics — print, share & saveConverterElectric CurrentConverterVoltageConverterElectric ResistanceConverterElectric ChargeConverterCapacitanceConverterInductanceConverterElectrical ConductanceConverterMagnetic Flux DensityConverterMagnetic FluxConverterElectric Field StrengthConverterMagnetic Field StrengthCalculatorOhm's LawV=IRCalculatorElectrical PowerP=IVCalculatorRC Time Constantτ=RCCalculatorCapacitor ChargeQ=CVCalculatorPower (I²R)P=I2RCalculatorCoulomb's LawF=k q1q2/r2CalculatorCapacitor EnergyE=½CV2CalculatorInductor EnergyE=½LI2CalculatorPower (V²/R)P=V2/RCalculatorWire ResistanceR=ρL/ACalculatorParallel-Plate CapacitanceC=εA/dCalculatorReal Power (Power Factor)P=S·cosφCalculatorThree-Phase PowerP=√3·VLIL·pfCalculatorCapacitive ReactanceXC=1/(2πfC)CalculatorInductive ReactanceXL=2πfLCalculatorLC Resonant Frequencyf=1/(2π√(LC))CalculatorForce on a Current-Carrying ConductorF=BILCalculatorMotional EMFε=BLvCalculatorCurrent DensityJ=I/ACalculatorMagnetic FluxΦ=BACalculatorTransformer Turns RatioVp/Vs=Np/NsCalculatorElectron Drift Velocityvd=I/(nAe)CalculatorConductance & ResistanceG=1/RCalculatorResistors in Parallel1/R = 1/R1 + 1/R2CalculatorResistors in SeriesR = R1 + R2 + R3CalculatorCapacitors in Series1/C = 1/C1 + 1/C2CalculatorCapacitors in ParallelC = C1 + C2CalculatorVoltage DividerVout = Vin × R2 / (R1 + R2)ReferenceAWG Wire Gauge Chart34-row reference tableReferenceWire Ampacity Chart (NEC 310.16)24-row reference table
Light & Optics
ToolDepth of Field CalculatorHyperfocal distance, near & far focus limitsToolField of View & Angle of View CalculatorAngle of view, coverage at a distance & 35 mm-equivalent focal lengthToolExposure Value (EV) & Sunny-16 CalculatorExposure triangle, EV, Sunny 16 & equivalent aperture/shutter/ISOConverterIlluminanceConverterLuminous FluxConverterLuminance (Brightness)CalculatorThin Lens Equation1/f = 1/do + 1/di
Data & Computing
ConverterData StorageConverterData Transfer RateReferenceExcel Keyboard Shortcuts29-row reference tableReferenceEssential Excel Functions28-row reference tableReferenceWindows Keyboard Shortcuts24-row reference tableReferenceAutoCAD Command Aliases32-row reference tableReferencemacOS Keyboard Shortcuts23-row reference table
Geometry & Symbols
ToolTriangle SolverSolve any triangle (SSS, SAS, ASA, SSA)ToolCircle Arc & Segment CalculatorRadius, chord, arc length, sagitta & areaToolTank Volume & Dipstick CalculatorLiquid volume, capacity, % full & strap chartToolRegular Polygon CalculatorAcross-flats ↔ across-corners, side, area, angles & bar weightConverterLengthConverterAreaConverterVolumeConverterAngleReferenceAlt Codes for Symbols63-row reference tableReferenceGreek Alphabet for Engineers24-row reference table
Radiation & Nuclear
Finance
ToolMortgage Payment Calculator (PITI)Full monthly payment (PITI), PMI drop-off & true costToolBreak-even Analysis CalculatorBreak-even units & revenue, contribution margin, profit & ROIToolDebt Payoff Calculator (Snowball vs Avalanche)Snowball vs avalanche — payoff time, interest & orderToolLoan Amortization CalculatorPayment, total interest, schedule & extra-payment payoffToolSavings & Investment Growth CalculatorEnding balance, contributions vs growth & the full scheduleToolRetirement Drawdown CalculatorHow long will my savings last — depletion curve & safe withdrawalConverterPercentage & RateCalculatorSimple InterestI = P · r · tCalculatorRule of 72 (Doubling Time)t = 72 / rCalculatorCompound Interest / Future ValueA = P(1 + r)nCalculatorCAGR (Compound Annual Growth Rate)CAGR = (A / P)1/n − 1CalculatorLoan & Mortgage PaymentPMT = P·r / (1 − (1 + r)−n)CalculatorFuture Value of Savings (Annuity)FV = PMT · ((1 + r)n − 1) / r
Cycling
ToolBicycle Gearing CalculatorWhole-drivetrain gear inches, gain ratio, speed & rangeToolSpoke Length CalculatorLeft & right spoke length from hub, rim & lacingToolCycling Power CalculatorWatts for a speed — or speed from watts — with the breakdownCalculatorBicycle Gear InchesGI = Dwheel · (chainring / cog)CalculatorBicycle Gain RatioGR = (Dwheel / 2 · chainring) / (Lcrank · cog)CalculatorBicycle Development / Roll-outdev = π · Dwheel · (chainring / cog)CalculatorBicycle Speed from Cadence & Gearv = cadence · π · Dwheel · (chainring / cog)
Automotive
ToolTire Size Calculator & ComparisonCompare two tire sizes: diameter, speedometer error & ride heightToolEngine Displacement & Compression Ratio CalculatorDisplacement in litres/cc/cu in & the static compression ratioToolGear Ratio & Vehicle Speed CalculatorRoad speed in every gear, top speed & cruising RPM
Travel
Solar
Music & Audio
ToolNote Frequency & Musical Tuning CalculatorNote ↔ frequency (Hz), cents, MIDI & the harmonic seriesToolBPM & Delay-Time CalculatorTempo ↔ delay/echo time in ms & Hz for every note valueToolSound Level, Distance & Combining Sources CalculatorHow dB falls with distance (inverse-square) & adding sources logarithmically
Astronomy
Home
ToolWall Framing CalculatorStud count, plates, drywall & cost estimateToolPlank Floor Layout PlannerCourses, stagger, last-row rip, planks & costToolTile Layout PlannerGrid, perimeter cuts, tiles, boxes & costToolStair Rise & Run CalculatorRisers, treads, stringer length & angleToolFence CalculatorPosts, sections, rails, even pickets & concreteToolDeck Board CalculatorCourses, joists, butt joints, border, screws & boardsToolRoof Rafter CalculatorRafter length, pitch angle, birdsmouth & countToolPaint CalculatorWall & ceiling area, coats, coverage → gallonsToolWallpaper CalculatorRolls, strips, pattern repeat & match wasteToolRainwater Harvesting CalculatorRoof catchment yield, yearly harvest & barrel fillToolGravel & Aggregate CalculatorTons, cubic yards & coverage for any areaToolBlock & Brick Wall CalculatorHow many blocks or bricks a wall takesToolRebar CalculatorBar count, length, weight & sticks to buyToolConcrete CalculatorSlab or column volume → cubic yards & bagsCalculatorPaint Needed for a Roompaint = wall area × coats / coverageCalculatorFlooring / Plank Boxes to Buyboxes = floor area × waste factor / coverage-per-boxCalculatorAir-Conditioner Size (Cooling BTU)cooling = floor area × cooling-load factorCalculatorElectric Heater / Space-Heater Sizeheating = floor area × heat-load factorCalculatorDehumidifier Size (Pints per Day)removal = floor area × moisture factorCalculatorConcrete Slab Volume (Cubic Yards)volume = area × thickness
3D Printing
Tool3D Print Cost CalculatorFilament, electricity, machine time & margin — per part & per spoolCalculatorFilament Length & Weightmass = ρ · (π/4) · d2 · LCalculatorFilament Cost of a Printcost = mass · priceCalculatorVolumetric Flow & Max Print Speedflow = layer height · line width · speedCalculatorLayer Count from Part Heightlayers = part height / layer height
Woodworking
ToolFrench Cleat DesignerConfigure, cut & lay out the wallToolCut List OptimizerPack parts onto the fewest boards (with kerf)ToolSheet Cut OptimizerNest parts onto the fewest sheets (2-D guillotine)ToolWood Movement CalculatorSeasonal shrink & swell of solid woodToolBoard Foot CalculatorPrice a lumber cut list in board feetToolCompound Miter & Bevel CalculatorMiter & bevel for sloped boxes & crown mouldingToolSegmented Ring CalculatorSegment length, miter angle & cut listToolBox Joint CalculatorEven finger & notch layout + cut listToolDovetail Layout CalculatorTail & pin spacing, angle & cut listToolShelf-Pin Hole LayoutSystem 32 spacing, hole count & listToolShelf Sag & Stiffness CalculatorWill it bow? — deflection, verdict & how to stiffen itCalculatorBoard FeetBF = T × W × L / 144CalculatorLumber CostCost = Board Feet × PriceCalculatorFrame Miter AngleMiter = 180° / NCalculatorShelf Sag (Deflection)δ = 5WL³ / (32 E b h³)ReferenceWood Species Hardness & Strength15-row reference tableReferenceWood Screw Pilot & Clearance Hole Chart11-row reference table
Gardening
ToolPlant & Row Spacing CalculatorHow many plants fit a bed — spacing, rows & square-foot gardeningToolFertilizer & N-P-K Application Rate CalculatorHow much fertiliser to apply for a target nutrient rate — bags & nutrient deliveredToolRaised Bed & Garden Soil Volume CalculatorHow much soil, compost or mulch a bed needs — bags & bulk
Food & Drink
ToolBread Dough CalculatorBaker’s-percentage weights, hydration, levain & per-loaf splitToolRoast Doneness PlannerCook time, pull temperature, carry-over rise & a serve-time scheduleToolMeal Timing PlannerBack-schedule every dish so the whole meal is ready at onceToolCoffee Brew Ratio CalculatorCoffee dose, water & yield from a brew ratioToolCake Pan Converter & Recipe ScalerSwap pan sizes & scale the recipe to matchCalculatorRecipe Serving ScalerNew = Original × (New servings / Original servings)CalculatorBaker's Hydration (%)Hydration % = 100 × Water / FlourCalculatorRoast & Meat Cook TimeCook time = Weight × Cook rate (min per lb)CalculatorRefrigerator Thaw TimeThaw time = Weight × Thaw rate (h per lb)CalculatorFrench Press RatioWater = Ratio × CoffeeReferenceOven Temperature & Gas Mark Chart11-row reference tableReferenceSafe Internal Cooking Temperatures7-row reference tableReferenceCups to Grams — Ingredient Weight Chart13-row reference table