Engineering Calculator

One calculator for the formulas engineers, technicians and students reach for every day: fifty of them, across mechanics, electrical work, machines and materials, heat and gases, fluids, waves and chemistry. Search by what you are doing — “voltage drop”, “braking distance”, “three phase”, “ideal gas” — or browse by subject, and the formula opens with a worked example. Every variable is a field with its own unit, and any of them can be the unknown: type into the fields you know and the rest are worked out, or press a symbol under “Solve for” to pick the unknown directly. When more values are filled in than the formula needs, the ones you typed most recently are used and the field that gives way says so, so a value is never silently ignored. Units are converted exactly (pounds, inches, psi and horsepower from their legal definitions, °C and °F with their offsets), the answer can be shown to three to ten significant figures, and the working is written out in SI units so it can be checked by hand or pasted into a report. The address keeps the formula and your values, so Copy link reopens exactly what you see, and Save as image or Print makes a record. Included: SUVAT motion (any three of displacement, both velocities, acceleration and time), projectile range and height, work, centripetal force, gravitation, pendulum period, density, Hooke’s law, stress, strain and Young’s modulus, efficiency, torque, gear ratios and cutting speed; Ohm’s law, dividers, parallel resistors, LED resistors, single- and three-phase power, cable voltage drop, wire resistance, capacitor energy and charge, RC time constant and filter cut-off, reactance, battery runtime and Coulomb’s law; heat energy and the ideal gas law; flow rate, hydrostatic pressure and Reynolds number; wavelength and frequency; and moles, molarity and dilution.

1. Search, or choose a subject and a formula.
2. Type the values you know and choose their units. Fields you leave alone are worked out.
3. Press a symbol under Solve for to make it the unknown, or simply type over a calculated field.
4. Read the working, set the precision, then copy the link or save the result.

• The formulas are the textbook ideal: no air resistance, friction, temperature drift or real-gas behaviour unless the note says otherwise. They are for estimates and checks, not as the only basis for a safety-critical design.
• Cable voltage drop counts conductor resistance only. Wiring rules (IS 732, BS 7671, the NEC) also set limits, derating and reactance for large cables.
• Where two answers are possible — a quadratic in time, or two launch angles for one range — the page picks the physical one and says which.
• Measured constants are given with their source: G from CODATA 2022 is good to about 0.002 %.
• Every calculation runs in your browser and works offline. Nothing you type is sent anywhere; your values are only in the page address, and only if you copy the link.

The values you typed most recently are used and the remaining field shows the worked-out value, marked Calculated. Type into it to make it an input; the oldest value then gives way.

Open SUVAT, enter the initial speed as u, 0 as v and the deceleration as a negative a. The displacement s is the stopping distance.

Open Cable voltage drop, enter the length, current and the drop you can accept (often 3 % of the supply), and leave the conductor size empty; choose the next standard size up.

Yes. The temperature is converted to kelvin with its offset before the formula is used, so 0 °C is 273.15 K.

They use the same formulas, with presets and extra figures around them; this page puts all of them in one place.