Science & Engineering Calculators — Free Online

Ohm's Law Calculator Solve for voltage, current, resistance or power — enter any two of the four.

Voltage Drop Calculator Estimate the voltage lost along a wire run from length, current and conductor size.

Resistor Color Code Calculator Decode 4/5/6-band resistor colours into a value — or reverse a value into bands.

Capacitor Charge Calculator Chart the charge or discharge curve of an RC circuit with time constant and energy.

Electrical Power Calculator Power in watts, kW and horsepower — plus energy use and running cost.

Force Calculator (F = ma) Solve Newton's second law for force, mass or acceleration.

Kinetic Energy Calculator Solve KE = ½mv² for energy, mass or velocity, with momentum and a curve.

Potential Energy Calculator Gravitational PE = mgh — solve for energy, mass or height, on any planet.

Density Calculator Solve for density, mass or volume, with unit choices and a materials table.

Molarity Calculator Solve for molarity, mass, molar mass or volume of a solution.

Ideal Gas Law Calculator Solve PV = nRT for any variable, in your choice of pressure, volume and temperature units.

Wavelength & Frequency Calculator Convert wavelength ↔ frequency, get the photon energy and the spectrum band.

pH Calculator Convert between [H⁺], pH, pOH and [OH⁻] and classify the acidity.

Torque Calculator Torque from force, lever length and angle — with the power at a given speed.

Gear Ratio Calculator Gear ratio, output speed and torque — single or compound, with road speed.

Projectile Motion Calculator Range, peak height, flight time and the full trajectory curve of a launch.

Subnet Calculator (IPv4 CIDR) Full IPv4 subnet breakdown: network, broadcast, mask, wildcard, host range and count.

Binary / Hex / Decimal Converter Convert a number between binary, octal, decimal and hexadecimal, with a breakdown table.

BTU Calculator (AC & Heating) Size an air conditioner or heater in BTU from room area, climate, sun and occupancy.

Half-Life Calculator Radioactive decay: find the remaining amount, elapsed time or half-life, with a decay curve.

Molecular Weight Calculator Molar mass of a chemical formula, with a per-element mass breakdown.

Electricity Cost Calculator Running cost of an appliance from its wattage, hours of use and your energy price.

Wind Chill Calculator How cold it feels from air temperature and wind speed, using the NWS formula.

Heat Index Calculator The "feels like" temperature from heat and humidity, using the NWS Rothfusz formula.

Dew Point Calculator Find the dew point from air temperature and relative humidity, with a comfort rating.

Bandwidth / Download Time Calculator Estimate download time from file size and connection speed, with throughput conversions.

Horsepower Calculator Compute engine horsepower from torque and RPM, or estimate quarter-mile trap speed.