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Physics formula

How to calculate kinetic energy

Kinetic energy is the energy an object has because it is moving.

See the formulaOpen calculator
Direct answer
Formula
KE = 0.5 * m * v^2

Use the table below to match each symbol with the right input. Keep units consistent before you start.

Kinetic energy formula
Start here when you only need the equation and variable names.
Formula
KE = 0.5 * m * v^2

Kinetic energy is the energy an object has because it is moving.

Variable meanings
Check each symbol, meaning, and unit before you calculate.
SymbolNameDescriptionUnit
KEKinetic energyEnergy of motion.J
mMassObject mass.kg
vVelocityObject speed.m/s
When to use this formula
Check that your situation matches the formula before you trust the result.
  • Works for moving objects when mass and speed are known and relativistic effects are not needed.
Step-by-step method
Follow these steps when you are solving it by hand.
  1. 1Convert mass to kilograms.
  2. 2Convert velocity to meters per second.
  3. 3Square the velocity.
  4. 4Multiply by mass and by 0.5.
Examples
These sample numbers show the order of operations and units.
Small object
m
2 kg
v
10 m/s
  1. 1.KE = 0.5 * 2 * 10^2
  2. 2.KE = 100 J
Result
The kinetic energy is 100 J.
Moving car
m
1,500 kg
v
25 m/s
  1. 1.KE = 0.5 * 1500 * 25^2
  2. 2.KE = 468750 J
Result
The kinetic energy is 468,750 J.
Mistakes to avoid
Small input or unit errors can change the answer a lot.
  • Mixing metric and imperial units before solving the kinetic energy formula.
  • Forgetting squared units such as m^2, m/s^2, or velocity squared.
  • Dropping negative signs when direction matters.
  • Rounding measured values too early in the calculation.
Open the Kinetic Energy Calculator
Open the calculator for the answer without rewriting the formula.

Enter your values in the related calculator, then compare the output with the hand method above.

Open Kinetic Energy Calculator
FAQs
Short answers for common formula questions.
Can I calculate Kinetic energy by hand?

Yes. Write the units next to each value, convert rates or measurements first, and round only the final answer.

Why does my Kinetic energy result differ from another calculator?

Most differences come from rounding, unit conversions, rate timing, or a slightly different version of the formula.

When is the Kinetic Energy Calculator better than hand math?

Open the Kinetic Energy Calculator to check several scenarios or skip the hand arithmetic.