Momentum Calculator

Find p = m x v for a single body, the total momentum of two bodies, or the final velocities in an elastic collision.

Momentum and collisions

Solve for

Mass 1 (kg) Velocity 1 (m/s) Momentum (kg m/s)

Mass 2 (kg) Velocity 2 (m/s)

Result: —

Momentum 1: —

Momentum 2: —

Total momentum: —

Velocities are signed, so a body moving the other way has a negative value.

Choose whether to find momentum, mass, velocity, total momentum or a collision result.
Enter the masses and velocities, using a negative velocity for motion the other way.
Read the result with the momentum of each body and their total.

Common questions about the free online momentum calculator.

Multiply the mass in kilograms by the velocity in metres per second. The answer is in kilogram metres per second.

Momentum equals mass times velocity, written as p = m x v, and it is a vector so the direction of travel matters.

The momentum is 6 kilogram metres per second, because 2 kilograms multiplied by 3 metres per second equals 6.

A negative value simply means the body is moving in the opposite direction to the one you chose as positive.

Yes. In any collision the total momentum before the impact equals the total momentum after it, as long as no outside force acts.

An elastic collision conserves both momentum and kinetic energy, so the bodies bounce apart with no energy lost as heat.

The calculator uses the standard one-dimensional formulas built from conservation of momentum and conservation of kinetic energy.

Momentum is mass times velocity and is a vector, while kinetic energy is half the mass times velocity squared and is a scalar.

No. Every momentum calculation runs locally in your browser, so the values you enter never leave your device.

Yes. It is completely free and unlimited, with no account, no sign-up and no restrictions on how much you use it.

Last updated: October 10, 2026