A unit-aware engineering calculator

In Equation Pad every value can carry its unit. Units are checked, cancelled and converted for you, so you never multiply by conversion factors again, and a wrong unit gives an error instead of a wrong answer.

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Typeset lines with units: a speed converted from km/h to m/s and loads in kN/m².

Write equations with units

F := 2.5 kN
A := 300 mm*450 mm = mm^2
sigma := F/A = MPa
v := 120 km/(1.5 h) = m/s
E := 3 kW*2 h = kWh

Automatic unit conversion

Write the unit you want after the =: = kN*m, = mm^2, = psi. Results without a requested unit use the unit system you choose: engineering SI (kN, m, mm, MPa), SI base units or US customary.

Every SI prefix, and the units engineers use

All the SI prefixes from quecto to quetta work with SI units: mm, µm, kN, MN, MPa, GPa, kWh, MBq, mGy and so on (type µ, μ or u for micro, and Ω or ohm). Built in as well: kNm, kN/m², psi, ksi, kip, kgf, tf, psf, pcf, bar, mmHg, rpm, gpm and hundreds more, and you can add your own units.

Units and variables side by side

A unit written straight after a number is always a unit, even when a variable has the same name: after m := 5 kg, the line F := m*9.81 m/s^2 = N works as expected. On the sheet units are upright and variables italic.

Live unit checking

Adding a force to a moment, or comparing a stress with a length, shows “Units do not match” on that line. Errors are counted in the status bar; click the count to jump to the first one.

Also used for

Equation Pad runs in your browser, with nothing to install, and we never see or store your calculations. Results must be checked by a competent person before they are relied on; see the disclaimer.

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