Potential Energy Calculator
Potential Energy490.500 J
Kilojoules0.491 kJ
Gravitational potential energy is the energy an object stores because of its position above a reference level in a gravity field. This calculator multiplies an object's mass, the gravitational acceleration, and its height to return the stored energy in both joules and kilojoules. It is the lifting counterpart to kinetic energy: raise an object and you bank energy that can be released the moment it falls.
Formula
PE = m × g × h
- PE
- Gravitational potential energy in joules (J)
- m
- Mass of the object in kilograms (kg)
- g
- Gravitational acceleration in m/s² (Earth ≈ 9.81)
- h
- Height above the reference level in metres (m)
How it works
- Enter the object's mass in kilograms and its height in metres above your chosen reference point (the floor, the ground, or any datum you pick).
- Set the gravitational acceleration. Earth's standard value of 9.81 m/s² is used by default, but you can change it to model the Moon (1.62), Mars (3.71), or any other body.
- The calculator multiplies mass by gravity by height and reports the result in joules, rounded to three decimals, alongside the equivalent in kilojoules.
Worked examples
A 10 kg box is lifted onto a shelf 5 metres above the floor on Earth.
- Identify the values: m = 10 kg, h = 5 m, g = 9.81 m/s².
- Multiply: 10 × 9.81 × 5 = 490.5.
PE = 490.5 J (about 0.491 kJ).
A 2 kg rock is held 3 metres above the surface of the Moon, where gravity is 1.62 m/s².
- Identify the values: m = 2 kg, h = 3 m, g = 1.62 m/s².
- Multiply: 2 × 1.62 × 3 = 9.72.
PE = 9.72 J (about 0.01 kJ), far less than on Earth for the same height.
Frequently asked questions
- What is gravitational potential energy?
- It is the energy an object possesses due to its vertical position in a gravitational field. Lift the object higher and you do work against gravity, which is stored as potential energy that converts back to motion when the object falls.
- Why does the height need a reference point?
- Potential energy is always measured relative to a chosen zero level. The height in PE = mgh is the distance above whatever datum you select, so the same object can have different potential-energy values depending on where you place the reference.
- How is potential energy different from kinetic energy?
- Potential energy depends on position (mass, gravity, and height), while kinetic energy depends on motion (mass and speed). As an object falls, its potential energy is converted into kinetic energy while the total mechanical energy stays roughly constant.
- Can I use this calculator for other planets?
- Yes. Just change the gravity field to the local value, for example 1.62 m/s² for the Moon or 3.71 m/s² for Mars, and the calculator returns the correct stored energy for that body.