Physics Calculators

Motion, energy, electricity and other physics formulas, solved for any unknown.

All physics calculators

• Acceleration CalculatorChoose what you want to find, enter the values you know, and the calculator works out acceleration, initial speed, final speed or time. Results for acceleration are also shown in metres per second squared and in multiples of g.
• Angular Velocity CalculatorPick one of four modes to find angular velocity, linear velocity or the radius of a circular path. Results can be shown in radians, degrees or revolutions per second, minute, hour, day, week, year or century.
• Buoyancy CalculatorEnter the volume of fluid an object displaces, the density of that fluid and the local gravity. The calculator returns the buoyant force and the mass of the displaced fluid, in metric and imperial units.
• Capacitor Energy & Charge CalculatorEnter the capacitance and the voltage across it, choose the units you want for charge and for energy, and get both results at once. The guide below explains the formulas and shows worked examples.
• Density CalculatorChoose whether you need density, mass or volume, fill in the two values you know with their units, and the result appears in several units at once. Below you will find the formula, typical densities and worked examples.
• Elastic Potential Energy CalculatorPick the quantity you want to find, enter the other two (spring constant and change in length, or energy and one of them), and read the answer in joules and other units. The guide explains Hooke's law and the energy formula.
• Flow Rate CalculatorPick a unit system, decide whether to work from the pressure difference or from the flow velocity, and describe the pipe. The calculator returns the discharge rate in several volume units.
• Half-Life CalculatorChoose which of the four quantities you want to find, enter the rest with their time units, and read the answer straight away. The guide covers the decay formulas, dating examples and the link between half-life, decay constant and mean lifetime.
• Ideal Gas Law CalculatorSelect the unknown, enter the other three properties of the gas in the units you have, and get the answer in the unit you prefer. The guide shows the equation, the special gas laws and a few worked cases.
• Impact Force CalculatorEnter the mass and impact speed of a moving body plus either the distance or the time it takes to stop, and the calculator returns the average and peak force. Switching modes lets you find a missing mass, speed, distance or duration instead.
• Kinetic Energy CalculatorChoose whether to solve for energy, mass or velocity, fill in the other two values in any units you like, and read the answer in several energy, mass or speed units at once.
• Ohm's Law CalculatorFill in any two of the four boxes and leave the rest empty. The calculator works out the missing pair using Ohm's law and the electric power formulas.
• Potential Energy CalculatorPick the quantity you want, enter the other two together with the local gravity, and get the answer in several units. Gravity starts at the Earth's standard value but can be changed for any planet.
• Reynolds Number CalculatorEnter the flow speed, a characteristic length and the fluid's viscosity to get the Reynolds number, the dimensionless figure that tells smooth laminar flow from turbulent flow.
• Terminal Velocity CalculatorEnter the mass, the frontal area, the drag coefficient, the density of the air and the gravity. The calculator returns the speed at which drag balances weight, in metric and imperial units.
• Thermal Expansion CalculatorChoose linear expansion, volumetric expansion or density change, enter the coefficient of thermal expansion and the two temperatures, and the calculator returns the size change and the final value. The guide explains the formulas and lists typical coefficients.
• Time Dilation CalculatorEnter how fast a clock is moving and how long it runs, and the calculator tells you how much time passes for an observer at rest, together with the percentage difference. The guide explains the Lorentz factor and shows how quickly the effect grows near light speed.
• Van der Waals CalculatorPick the quantity you want, supply the other three together with the gas constants a and b, and the calculator applies the van der Waals correction to the ideal gas law. The guide explains the equation, gives constants for common gases and notes where the model stops working.