Centripetal Force Calculator
Enter the mass, speed and radius of the circle to find the inward force.
This result is an estimate only. Double-check important figures before relying on them.
How it is calculated
- Acceleration = speed² ÷ radius
- Force = mass × acceleration
- Time for one circle = 2π × radius ÷ speed
For the energy of the same motion, use the kinetic energy calculator.
Worked example
A 1,000 kg car at 20 m/s (72 km/h) round a 50 m radius bend:
- Acceleration = 400 ÷ 50 = 8 m/s² (0.82 g)
- Force = 8,000 N
Why your number may differ
This is the required force for a perfect circle at constant speed. It does not include banking of the road or the actual grip available.
Frequently asked questions
What is centripetal force?
The inward force needed to keep an object moving in a circle. It acts towards the centre. For a car it is supplied by tyre friction.
What is the formula?
F = m × v² ÷ r, where m is the mass, v the speed and r the radius.
Why does speed matter so much?
The force grows with the square of the speed. Taking a bend twice as fast needs four times the grip.