Calculate it right, and understand why.
115 free engineering calculators. Each one gives the number, shows the formula and its assumptions, and works an example you can check by hand.
- 115 calculators
- 944 reference checks
- 442 cited sources
- Free no sign-up
Popular calculators
- MaritimeFuel consumption and voyage costFuel burned, time at sea, bunker cost and CO₂ for a passage from distance, speed and engine power or daily consumption.
- Fluids and pumpsPipe flow and pressure dropVelocity, Reynolds number, Darcy friction factor (Colebrook, Swamee–Jain) and pressure drop for a straight pipe with fittings.
- ElectricalCable sizing and voltage dropVoltage drop, power loss and the minimum IEC conductor size for DC, single-phase and three-phase circuits from current, length, material and allowed drop.
- MaritimeCII rating estimatorAttained and required operational CII with the A–E rating, from ship type, capacity, annual fuel or CO₂ and distance.
- StructuralBeam deflection and bending stressMaximum bending moment, bending stress, deflection and reactions for simply supported, cantilever and fixed beams with standard sections.
- MechanicalBolt torque and preloadPreload and tightening torque for ISO metric bolts by the VDI 2230 method, with property class, friction, proof load and preload scatter.
- ThermalHeat exchanger LMTDLMTD for counter, parallel and 1-2 shell-and-tube flow, duty from either stream, F correction, fouling and required area from U.
- Fluids and pumpsPump and fan affinity lawsFlow, head or pressure and power at a new speed or impeller diameter from one known operating point, with efficiency and specific speed.
Browse by field
How the numbers are checked
Every calculator is tested against a textbook, a standard or a hand calculation, and a new version goes live only when every check passes. Each page lists its assumptions and sources, and has a button that runs its checks in your own browser.