Potential Energy Calculator

What is potential energy?

An object held at a height is able to do work if it falls. The energy it has because of its position is gravitational potential energy: E = m × g × h. With mass in kilograms, height in metres and g = 9.81 m/s² the result is in joules.

The meaning is simple: m × g is the weight of the object in newtons. The work done lifting that weight through a height h is stored in the object as potential energy.

Where is height measured from?

You choose the zero level: the floor, a table top or sea level. What matters in calculations is the difference between two levels. An object that descends from 10 metres to 4 metres loses the energy corresponding to 6 metres of height.

Example

A person with a mass of 75 kg climbing 10 metres gains 75 × 9.80665 × 10 = 7355 J of potential energy. That is about 7.4 kJ, or 0.002 kWh.

Conversion to kinetic energy

As an object falls, potential energy turns into kinetic energy. Without friction, m × g × h = ½ × m × v² gives the impact speed v = √(2 × g × h), which is exactly the free fall formula.

Limits

The formula applies to heights over which gravitational acceleration stays constant. For very large heights, such as satellite orbits, the law of universal gravitation is needed.