Science & Engineering Calculators

Enter any two of voltage, current, resistance or power and get the other two, with every formula in the Ohm’s law wheel shown.

Calculate voltage drop over a cable run from length, size and current, and check it against the usual 3% and 5% limits.

Work out what any appliance costs to run per hour, day, month and year from its wattage and your tariff.

Calculate density, mass or volume from the other two, with a reference table of common materials and a float-or-sink check.

Calculate the wind chill temperature — how cold the air feels on exposed skin — using the official North American formula.

Calculate the heat index — how hot it feels once humidity is accounted for — with the official NWS regression and risk categories.

Calculate dew point from temperature and humidity using the Magnus formula, with what each dew point actually feels like.

Solve for molarity, mass, volume or moles when preparing a solution — enter any three of the four to find the fourth.

Calculate the molecular (molar) weight of a chemical formula — supports parentheses and hydrates like CuSO₄·5H₂O.

Solve PV = nRT for pressure, volume, moles or temperature, with unit conversion and a check on how ideal the conditions really are.

Convert between pH, pOH and hydrogen ion concentration, and find the pH of a strong or weak acid or base from its concentration.

Read a resistor's value and tolerance from its colour bands — supports 3-band, 4-band and 5-band resistors.

Combine capacitors in series or parallel, with total capacitance, stored energy, charge and the voltage each series capacitor carries.

Calculate the RC time constant, charging and discharging voltage over time, and the filter cutoff frequency of a resistor–capacitor circuit.

Convert AWG to diameter, cross-section and resistance per metre, with metric equivalents and reference ampacity figures.

Calculate horsepower from torque and RPM, or convert between horsepower, kilowatts and metric horsepower.

Estimate engine horsepower from quarter-mile elapsed time or trap speed — the classic drag racing horsepower formulas.

Estimate the air conditioner size (in BTU) a room needs, from its dimensions, insulation, sun exposure and occupancy.

Calculate the escape velocity and surface gravity of a planet, moon or star from its mass and radius.

Calculate kinetic energy, mass or velocity from KE = ½mv², with momentum and stopping distance alongside.

Calculate the range, maximum height and flight time of a projectile from its launch speed and angle.

Calculate terminal velocity from mass, drag coefficient and frontal area, with the distance and time needed to reach it.

Work out gear ratio from tooth counts, with output speed, torque multiplication, and multi-stage or compound gear trains.

Calculate the heat energy needed to change a substance's temperature from Q = mcΔT, solving for any variable.

Convert between wavelength, frequency and photon energy for light, sound and any other wave.

Calculate the electrostatic force between two charges, or solve for charge or separation, with the force compared against gravity.

Combine resistors in series or parallel, with the current and power dissipated in each one when a voltage is applied.

Combine multiple sound sources, convert between decibels and ratios, and work out how loudness falls with distance.