Momentum Calculator
Enter a mass and a speed to get the linear momentum in kg·m/s — plus the kinetic energy — and see how an object's motion adds up.
Momentum and energy at once
Enter the mass and velocity and the calculator returns the momentum (mv) in kg·m/s and the kinetic energy (½mv²) in joules together.
Use SI units
Mass in kilograms and velocity in metres per second give momentum in kg·m/s — divide km/h by 3.6 to get m/s before you start.
What is momentum?
The quantity of motion
This momentum calculator turns two measurements, the mass in kilograms and the velocity in metres per second, into the linear momentum in kg·m/s, alongside the kinetic energy in joules. Momentum is a measure of how much motion an object has — formally its mass multiplied by its velocity. The heavier or faster something moves, the more momentum it carries, and the harder it is to bring to a stop or push off course. It is the quantity that stays conserved when objects collide, which is why physicists reach for it first when they analyse impacts, recoil, and rocket propulsion. Unlike energy, momentum is a vector: it has both a size and a direction.
Enter a mass in kilograms and a speed in metres per second to get the momentum in kg·m/s and the kinetic energy instantly.
Momentum is simply mass multiplied by velocity, and the kinetic energy is half the mass multiplied by the velocity squared.
p = m × vSuppose a 10 kg object is travelling at 5 m/s. Multiply the mass by the velocity — 10 × 5 — to get a momentum of 50 kg·m/s. The kinetic energy is ½ × 10 × 5² = 125 J. Momentum keeps velocity to the first power, so it rises in direct proportion to speed, while the kinetic energy squares the velocity and climbs far more steeply. Use kilograms and metres per second and the momentum comes back in kg·m/s and the energy in joules.
The formula is exact, but a couple of practical points are worth keeping in mind.
One direction and consistent units
This calculator gives the linear momentum of an object moving in a straight line and reports its magnitude — it does not track direction or angular momentum (a spinning wheel), and it ignores relativistic effects that only matter near the speed of light. Keep your units consistent — kilograms for mass and metres per second for velocity — or the result will be wrong: convert km/h to m/s by dividing by 3.6 before you enter the speed.