Potential Energy Calculator
Calculate gravitational potential energy, or the energy stored in a spring.
Please note: Results use idealised models — point masses, no air resistance, ideal gases and uniform materials. Real experiments deviate. Use these for study and estimation, not for engineering sign-off.
What the Potential Energy Calculator does
Potential energy is energy stored by position. Lift a mass and you store its weight times the height gained; stretch a spring and you store the area under its force curve. In both cases the stored energy is released as motion when the object is let go.
Formula
PE = m × g × h (gravitational)PE = ½ × k × x² (elastic, Hooke’s law)Impact speed v = √(2gh)
Inputs explained
| Input | Unit | Required | Notes |
|---|---|---|---|
| Type of potential energy | one of 2 options | Yes | — |
| Mass | number | In some modes | Shown Type of potential energy is Gravitational (PE = mgh). |
| Mass unit | one of 6 options | In some modes | Shown Type of potential energy is Gravitational (PE = mgh). |
| Height | number | In some modes | Shown Type of potential energy is Gravitational (PE = mgh). |
| Height unit | one of 9 options | In some modes | Shown Type of potential energy is Gravitational (PE = mgh). |
| Gravitational acceleration | m/s² | Optional | Standard gravity on Earth is 9.80665 m/s². The Moon is 1.62, Mars 3.72. Accepts 0 or more. Shown Type of potential energy is Gravitational (PE = mgh). |
| Spring constant | N/m | In some modes | The force needed per metre of stretch. A car suspension spring is 20,000–40,000 N/m. Accepts more than 0. Shown Type of potential energy is Elastic — a spring (PE = ½kx²). |
| Stretch or compression | number | In some modes | Shown Type of potential energy is Elastic — a spring (PE = ½kx²). |
| Stretch or compression unit | one of 9 options | In some modes | Shown Type of potential energy is Elastic — a spring (PE = ½kx²). |
How to use it
- Choose Type of potential energy.
- Fill in the remaining inputs the form shows for your choice.
- Select Calculate.
Worked example
A 75 kg person standing on a 10 m platform.
- Mass
- 75 kg
- Height
- 10 m
- Gravity
- 9.80665
PE = 75 × 9.80665 × 10 = 7,355 J. Dropping that far, they would land at 14.005 m/s — about 50.4 km/h.
Frequently asked questions
Potential energy relative to what?
Whatever height you call zero. Only changes in potential energy matter physically, so the reference point is yours to choose.
Why is there a ½ in the spring formula but not the gravity one?
Gravity applies a constant force, so energy is force times distance. A spring’s force grows from zero as it stretches, so you use the average force — half the final value.