Kinetic Energy Calculator

Calculate kinetic energy, mass, or velocity of a moving object

Formula shown2 inputs definedUpdated Nov 2025By CalcuTotal TeamFree, no sign-up

Quick Summary

Use this when you need:

Get accurate results in seconds
Solve physics problems or verify homework
Solve for any unknown variable

You’ll need:Mass, Velocity

You’ll get:Kinetic energy

How this is calculated

The formula is always visible so you can verify the math and explain your numbers to anyone who asks.

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What these terms mean

Mass

Mass used in the calculation.

Velocity

Velocity used in the calculation.

Kinetic energy

Kinetic energy used in the calculation.

When to use this calculator

Use this calculator when you need to quickly compute kinetic energy calculator with accurate, verified formulas.

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Last updated: November 19, 2025

Kinetic energy calculator explained

Kinetic energy (KE) describes how much energy an object has because it is moving. This calculator applies $KE = \\tfrac12 m v^2$ , converts units, and lets you solve for mass or velocity when the other values are known.

How the conversion works

The formula is:

KE = \\frac{1}{2} m v^2

where $m$ is mass and $v$ is speed. Solving for velocity gives $v = \\sqrt{2KE / m}$ , and solving for mass gives $m = 2KE / v^2$ . Unit conversions follow SI standards (e.g., pounds to kilograms, mph to m/s).

Units and conversions

Quantity	Units	Notes
Mass $m$	kg, g, lb, oz	Converted to kilograms internally.
Velocity $v$	m/s, km/h, mph, ft/s	Converted to m/s before squaring.
Energy $KE$	J, kJ, cal, kcal	Base unit is Joule (kg·m²/s²).

Worked examples

Cart moving at 20 m/s
$m = 10$ kg, $v = 20$ m/s:

KE = 0.5 \\times 10 \\times 20^2 = 2{,}000\\ \\text{J}

Find speed from energy
A 1,200 kg car has 200 kJ of kinetic energy.

v = \\sqrt{2 \\times 200{,}000 / 1{,}200} = 18.26\\ \\text{m/s} = 40.8\\ \\text{mph}

Tips and pitfalls

Always use absolute speed; kinetic energy depends on speed squared, so doubling speed quadruples energy.
Convert rotational kinetic energy separately; this calculator covers translational motion only.
For relativistic speeds near light speed, use relativistic formulas since $\\tfrac12 m v^2$ underestimates energy.
When working with calories, remember 1 cal = 4.184 J; the calculator handles this automatically.

References and further reading

Frequently Asked Questions