Energy Calculator
Kinetic, potential and work energy.
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Work out the energy in a moving object, an object held at height, or a force applied over a distance — all in joules. Pick the type of energy, enter the values, and the result appears in joules, kilojoules, and calories.
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Energy — The Quick Answer
Kinetic energy is ½mv², gravitational potential energy is mgh, and work done is force times distance. All are measured in joules (J).
Shortcut
KE = ½ × m × v² | PE = m × g × h | W = F × d
The three energy formulas
| Type | Formula | Inputs | Unit |
|---|---|---|---|
| Kinetic energy | KE = ½mv² | mass (kg), velocity (m/s) | joules |
| Potential energy | PE = mgh | mass (kg), height (m) | joules |
| Work done | W = F × d | force (N), distance (m) | joules |
Because velocity is squared in kinetic energy, doubling speed quadruples the energy. That's why stopping distances rise so steeply with vehicle speed.
How It Works
The Formulas
Three ways energy shows up
Formula
KE = ½ × m × v² PE = m × g × h W = F × d
Variables
Kinetic energy
Energy of motion. Grows with the square of velocity, so fast objects carry immense energy.
Potential energy
Energy stored by height against gravity. Uses g ≈ 9.80665 m/s² on Earth.
Work done
Energy transferred when a force moves something through a distance. A watt is one joule per second.
Note: All energy is measured in joules (J), the SI unit. 1 kilojoule (kJ) = 1000 J, and 1 calorie ≈ 4.184 J.
Last updated: October 6, 2026
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Frequently Asked Questions
How do I calculate kinetic energy?
Use KE = ½ × m × v². A 2 kg object moving at 3 m/s has a kinetic energy of ½ × 2 × 3² = 9 joules. Note the velocity is squared, so speed matters far more than mass.
What is the formula for potential energy?
Gravitational potential energy is PE = m × g × h, where m is mass in kg, g is gravitational acceleration (≈ 9.81 m/s² on Earth), and h is height in metres. Lifting a 5 kg box 2 m stores 5 × 9.80665 × 2 ≈ 98 J.
How is work different from energy?
Work is the transfer of energy when a force moves an object over a distance: W = F × d. It's measured in the same unit, the joule, because doing work on an object changes its energy.
Why does doubling speed increase kinetic energy fourfold?
Because kinetic energy depends on velocity squared (v²). Doubling v makes v² four times larger, so KE quadruples. This is why crash forces rise so dramatically with speed.