Potential Energy Calculator (PE = mgh)
Calculate gravitational potential energy, mass, or height with PE = mgh, with a choice of gravity for other planets.
Gravitational potential energy
Lifting something stores energy in it. That stored energy — gravitational potential energy — is the work gravity will do if you let the object fall again, and it depends on three things: mass, height, and the strength of gravity.
PE = m × g × h
Mass in kilograms, height in metres, and g in m/s² give energy in joules. Switch g to another world to see how the same lift compares on the Moon or Mars.
Height from where?
Potential energy is always measured relative to a reference level you choose — usually the ground or the floor. Only the change in height matters physically, so picking a different zero point shifts every value by the same amount and changes nothing real. Use whatever reference makes the problem easiest.
Turning into motion
Drop the object and its potential energy converts intokinetic energy. Setting mgh = ½mv² and cancelling the mass gives v = √(2gh) — the impact speed, independent of how heavy the object is. This calculator shows that speed alongside the energy.
Worked example
A 10 kg mass held 5 m up has PE = 10 × 9.807 × 5 ≈ 490 J. Let it go and it lands at √(2 × 9.807 × 5) ≈ 9.9 m/s. On the Moon the same lift stores only about 81 J, and it lands at a gentle 4 m/s — the same drop, six times less energy.
Height relative to what?
Gravitational potential energy has no absolute value — only differences matter — so the answer depends entirely on where you decide zero is. That is a choice, not a fact, and it must be the same choice throughout a calculation. The formula also assumes g is constant, which holds near the surface but fails over large heights: at orbital distances you need the full inverse-square treatmentinstead.