Science & Engineering

Physics, electronics and chemistry calculators that solve for any value and show the formula and working. 21 tools, all free.

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Electronics

Ohm’s law, voltage dividers and resistor colour codes.

Ohm's Law CalculatorNewEnter any two of voltage, current, resistance and power to get the other two, in the units you choose, with the formula and working shown.

Resistor Colour Code CalculatorNewRead a resistor’s colour bands — 3, 4, 5 or 6 — or find the bands for a value, with tolerance, temperature coefficient and E-series checks.

Voltage Divider CalculatorNewEnter any three of input voltage, the two resistors and output voltage to get the fourth, with the current, power and output resistance.

Physics

Speed, acceleration, force, momentum, energy, power, pressure, and the wavelength and frequency of light and sound.

Speed, Distance and Time CalculatorNewEnter any two of speed, distance and time to get the third, in km/h, mph, m/s or knots, with the time in hours and minutes and the pace per km and mile.

Power Calculator (P = E/t)NewEnter any two of power, energy and time to get the third, in watts, kilowatts or horsepower, joules, kWh or calories, and seconds to days.

Acceleration CalculatorNewEnter any three of starting velocity, final velocity, acceleration and time to get the fourth, with the distance covered — 0 to 100 km/h, braking and more.

Force Calculator (F = ma)NewNewton’s second law: enter any two of force, mass and acceleration to get the third, in newtons, kilograms, g, pounds and more.

Pressure Calculator (P = F/A)NewEnter any two of pressure, force and area to get the third, then read the pressure in pascals, bar, atm, psi, mmHg and torr side by side.

Kinetic Energy CalculatorNewEnter any two of kinetic energy, mass and speed to get the third — joules, kilojoules, kWh or calories; kg or pounds; m/s, km/h or mph.

Potential Energy Calculator (E = mgh)NewGravitational potential energy, E = mgh: enter any three of energy, mass, gravity and height to get the fourth, on Earth, the Moon or Mars.

Wavelength and Frequency CalculatorNewConvert between wavelength and frequency for light, radio and sound (v = f × λ), with photon energy and the part of the spectrum for light.

Momentum Calculator (p = mv)NewEnter any two of momentum, mass and velocity to get the third, in kg·m/s, N·s or lb·ft/s, with the kinetic energy that goes with it.

Chemistry

The periodic table, molar mass from any formula, moles, molarity and dilutions.

Periodic Table of the ElementsNewAll 118 elements with atomic number, IUPAC standard atomic weight, group, period and block. Find any element by name or symbol, or browse it as a list.

Molar Mass CalculatorNewMolar mass of any chemical formula — brackets, hydrates like CuSO4·5H2O and all 118 elements — with composition by mass and grams to moles.

Mole Calculator (Grams, Moles, Particles)NewConvert between grams, moles and number of particles with Avogadro’s constant. Type the molar mass, or just the formula, and fill in any two values.

Molarity CalculatorNewEnter any three of mass, molar mass (or just the formula), volume and molarity to get the fourth — how many grams to weigh for a solution.

Dilution Calculator (C1V1 = C2V2)NewEnter any three of stock concentration, stock volume, final concentration and final volume to get the fourth, with how much solvent to add.

Engineering

Gear ratios, rpm and surface speed, torque, and engineering notation with SI prefixes.

Engineering Notation ConverterNewWrite any number in engineering notation, scientific notation, with an SI prefix (4.7 kΩ, 22 nF) and as E notation, to the significant figures you choose.

Torque CalculatorNewTorque from a force on a lever (τ = F × r) or from power and rpm (P = τω): enter any two values to get the third, in N·m, kgf·m, lbf·ft or lbf·in.

RPM Calculator (Speed and Diameter)NewEnter any two of rpm, diameter and surface speed to get the third: a wheel’s rpm at a road speed, or a drill or lathe’s spindle speed for a cutting speed.

Gear Ratio CalculatorNewEnter any three of driver teeth, driven teeth, input speed and output speed to get the fourth, with the gear ratio and what it does to speed and torque.