Engineering and Trade Calculators
These calculators cover the everyday sums of engineers, technicians and tradespeople: beam deflection and bending moments, steel weights and rebar, bolt torque and gear ratios, wire sizes and three-phase power, LED resistors and PCB trace widths, heat loss and thermal expansion, pipe pressure drop and pump power, duct sizes, rafters and deck materials, sheet metal bend allowances and engine displacement.
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Beam deflection, bending moment, buckling, section properties, steel weight, rebar, concrete mix, masonry, paving, earthwork and survey distance calculators.
Beam Deflection Calculator
Maximum deflection and slope of simply supported and cantilever beamsShear and Bending Moment Calculator
Shear force and bending moment diagrams for beams with point and distributed loadsColumn Buckling Calculator
Euler critical buckling load and slenderness for columns with different end conditionsSection Properties Calculator
Area, centroid, moment of inertia and section modulus of common cross-sectionsSteel Weight Calculator
Weight of steel plates, bars, tubes, angles and beams by size and lengthRebar Calculator
Number, length and weight of reinforcing bars for a slab or footingConcrete Mix Ratio Calculator
Cement, sand, aggregate and water quantities for a nominal concrete mixBrick and Mortar Calculator
Bricks or blocks and mortar needed for a wall, with openings and wasteAsphalt Calculator
Tons of asphalt for a driveway or paving area from size and thicknessCut and Fill Calculator
Earthwork volumes from a grid of existing and proposed levelsCoordinate Distance Calculator
Distance and bearing between two latitude/longitude points
Torque and power, gears, pulleys, bolt torque, springs, stress and strain, bearing life, hydraulics, tap drills and machining speeds and feeds.
Torque and Power Calculator
Convert between torque, power and speed in metric and imperial unitsGear Ratio Calculator
Gear ratio, output speed and torque for gear trainsPulley and Belt Calculator
Pulley speeds, belt length and belt speed for two-pulley drivesBolt Torque Calculator
Tightening torque and preload for metric and UNC/UNF boltsSpring Calculator
Rate, stress and deflection of helical compression springsStress and Strain Calculator
Stress, strain, Young's modulus and elongation under axial loadBearing Life Calculator
L10 rating life of ball and roller bearings from load and speedHydraulic Cylinder Calculator
Cylinder force, speed and flow from bore, rod and pressureTap Drill Size Calculator
Tap drill size and thread engagement for metric and unified threadsSpeeds and Feeds Calculator
Spindle RPM and feed rate for milling, drilling and turning
Wire sizing, single and three-phase power, power factor correction, transformer sizing, battery runtime, solar arrays and generator sizing.
Wire Size Calculator
Conductor size for a load from ampacity and voltage dropThree-Phase Power Calculator
kW, kVA and amps for single-phase and three-phase circuitsPower Factor Correction Calculator
Capacitor kVAR needed to raise power factorTransformer Sizing Calculator
Transformer kVA and primary/secondary currents for a loadBattery Runtime Calculator
How long a battery or UPS runs a load, with efficiency and depth of dischargeSolar Panel Calculator
Panels, array size and battery bank for a daily energy needGenerator Size Calculator
Generator wattage from running and starting loads
LED resistor, voltage divider, series and parallel, capacitor code, RC filter, 555 timer, impedance, op-amp gain, PCB trace width and decibel calculators.
LED Resistor Calculator
Series resistor for one or more LEDs from supply voltage and currentVoltage Divider Calculator
Output voltage or resistor values for a two-resistor dividerSeries and Parallel Calculator
Total resistance, capacitance or inductance in series and parallelCapacitor Code Calculator
Capacitance and tolerance from 3-digit capacitor codes, and backRC Filter Calculator
Cutoff frequency and time constant of RC and RL filters555 Timer Calculator
Frequency and duty cycle for 555 astable and monostable circuitsReactance and Impedance Calculator
Capacitive and inductive reactance, RLC impedance and resonanceOp-Amp Gain Calculator
Gain and output of inverting, non-inverting and differential op-amp circuitsPCB Trace Width Calculator
Trace width for a current and temperature rise per IPC-2221Decibel Calculator
Convert power and voltage ratios to dB, dBm and dBW and back
Conduction heat loss and U-values, thermal expansion, specific heat energy, heat exchanger LMTD and water heating time calculators.
Heat Loss Calculator
Conduction heat loss and U-value through walls and insulation layersThermal Expansion Calculator
Linear and volumetric expansion of materials with temperatureSpecific Heat Calculator
Heat energy to raise or lower a material's temperatureHeat Exchanger LMTD Calculator
Log mean temperature difference and duty for heat exchangersWater Heating Time Calculator
Time and energy to heat water with a given heater power
Flow rate, Reynolds number, pipe pressure drop, pump power, Bernoulli, hydrostatic pressure, tank volume and orifice flow calculators.
Flow Rate Calculator
Volumetric flow rate, velocity and pipe area conversionsReynolds Number Calculator
Reynolds number and flow regime for pipe flowPipe Pressure Drop Calculator
Friction loss in pipes with Darcy-Weisbach and the Colebrook equationPump Power Calculator
Hydraulic and shaft power from flow, head and efficiencyBernoulli Equation Calculator
Solve Bernoulli's equation for pressure, velocity or heightHydrostatic Pressure Calculator
Pressure at depth in a fluid and force on a submerged surfaceTank Volume Calculator
Total and filled volume of cylindrical, rectangular and spherical tanksOrifice Flow Calculator
Flow through an orifice or nozzle from pressure drop
Duct sizing, air changes per hour and water pipe sizing calculators for ventilation, heating, cooling and plumbing design.
Board foot, rafter, wall framing, deck, drywall, miter angle and baluster spacing calculators for carpenters, builders and woodworkers.
Board Foot Calculator
Board feet and cost of lumber from thickness, width and lengthRafter Calculator
Rafter length, plumb and seat cuts from span and roof pitchWall Framing Calculator
Studs, plates and headers for a framed wallDeck Calculator
Deck boards, joists, beams and fasteners for a rectangular deckDrywall Calculator
Drywall sheets, screws, tape and joint compound for a roomMiter Angle Calculator
Miter and bevel angles for polygons and crown moldingBaluster Spacing Calculator
Baluster count and even spacing for a railing
Bend allowance, sheet weight, gauge conversion, cone flat pattern, press brake tonnage, punching force and fillet weld calculators for fabricators.
Bend Allowance Calculator
Bend allowance, bend deduction and flat length using the K-factorSheet Metal Weight Calculator
Weight of sheet and plate by material, gauge and sizeSheet Metal Gauge Converter
Convert sheet metal gauge numbers to thickness for each materialCone Flat Pattern Calculator
Flat layout of a cone or truncated cone for rolling sheet metalPress Brake Tonnage Calculator
Bending force for air bending by thickness, die opening and materialPunching Force Calculator
Force to punch or blank a hole from perimeter, thickness and shear strengthWeld Size Calculator
Fillet weld strength, size and filler metal needed
Engine displacement, compression ratio, horsepower and gear speed calculators for engine builders and drivetrain planning.
Engine Displacement Calculator
Engine displacement from bore, stroke and cylindersCompression Ratio Calculator
Static compression ratio from bore, stroke and chamber volumesHorsepower Calculator
Horsepower from torque and RPM, or from weight and quarter-mileGear Speed Calculator
Vehicle speed per gear from RPM, ratios and tire size
Which tool do I need?
Check whether a beam will sag too much
Enter the span, load and section to get the maximum deflection and compare it with L/360 or another limit.
Pick the right wire for a circuit
Enter the load and run length to get a conductor size that meets ampacity and keeps voltage drop in range.
Choose the resistor for an LED
Enter the supply, the LED forward voltage and the current to get the resistor value, the nearest standard part and its power rating.
Lay out a sheet metal part before bending
Enter the thickness, inside radius, angle and K-factor to get the bend allowance and flat length.
Estimate lumber for a framing or deck job
Work out studs and plates for a wall or boards and joists for a deck, then price the board feet.
About Engineering Calculators
Each one shows the formula it uses, works in SI and US customary units with exact conversions, and names the standard or handbook its constants come from, such as IPC-2221 for trace widths, ISO 281 for bearing life or the NEC tables for conductor ampacity. Material properties are typical published values that you can overwrite with the figures from your supplier or specification.
Results are for checking, learning and preliminary design. Anything that carries load, current, pressure or people must be confirmed by a qualified engineer or licensed tradesperson against the code that governs your project. Everything runs in your browser, so project numbers stay on your device.
Guides
- Beam Deflection Formulas: Where 5wL⁴/384EI Comes From and When L/360 AppliesHow the standard beam deflection formulas are derived, what E and I really control, which deflection limits the codes set, and the mistakes that make a beam bounce.
- How to Size Electrical Wire: Ampacity, Derating and Voltage DropReading NEC Table 310.16 properly: terminal temperature limits, the 125% continuous-load rule, ambient and bundling derating, small-conductor breaker caps and when voltage drop decides the gauge.
- LED Current-Limiting Resistors: The Formula and the JudgmentWhy an LED needs a resistor, how R = (Vs − n·Vf) / I comes from the diode curve, how much headroom to leave, and how to wire series and parallel strings safely.
- Bend Allowance, Bend Deduction and the K-Factor ExplainedWhere the neutral axis sits in a bend, how bend allowance, setback and bend deduction relate, how to measure your own K-factor from a test strip, and why tight air bends need a smaller K.
Frequently asked questions
Which design codes do the engineering calculators follow?
Each calculator names its source, for example AISC beam formulas, the NEC ampacity table, IPC-2221 for PCB traces and ISO 281 for bearings. Where codes differ between countries, the tool says which one it uses and lets you change the limits.
Can I use these results to sign off a design?
No. They are reliable for checking, learning and early sizing, but a structure, electrical installation or pressure system needs a qualified professional to apply the governing code, load combinations and safety factors.
Do the engineering tools work in metric and imperial units?
Yes. Every calculator accepts SI and US customary inputs and converts with exact factors, so you can enter millimetres and read inches or kilonewtons and read pounds-force.
Where do the material properties come from?
From published typical values in handbooks and standards, such as steel at 200 GPa and 7,850 kg/m³. They are labelled as typical and can be overwritten with the values for your exact grade or product.
Is there a blog post explaining each calculator?
Yes. Every engineering calculator links to its own guide that derives the formula, works an example and lists the common mistakes and limits.