# Centripetal Force Calculator

URL: https://speedycalculator.com/calculators/physics/centripetal-force/
Last updated: 2026-10-25

> The centripetal force calculator finds the inward force needed to keep a mass moving in a circle, F = mv² ÷ r, and the centripetal acceleration.

## Inputs

- Mass (kg, lb, g, oz, st)
- Speed (m/s, km/h, mph, ft/s, knots)
- Radius (m, cm, mm, km, in, ft, yd, mi)

## Results

- Centripetal force
- Centripetal acceleration

## Formula

```
F = m v² ÷ r
a = v² ÷ r
```

## Explanation

An object moving in a circle constantly changes direction, which requires a force toward the centre, from tension, friction or gravity.

### How to use the Centripetal Force Calculator

- **Mass**
- **Speed**
- **Radius**
- Want to work backwards? Type a value into **Centripetal force** and **Speed** is calculated for you.

Results update as you type, and every field accepts the units shown in its menu.

### How it works

Square the speed, multiply by mass and divide by the radius.

### Inputs explained

FieldWhat to enterMassUnits: kg, lb, g, oz, stSpeedUnits: m/s, km/h, mph, ft/s, knotsRadiusUnits: m, cm, mm, km, in, ft …

### What each result means

- **Centripetal force** = [Mass] × [Speed]^2 ÷ [Radius]
- **Centripetal acceleration** = [Speed]^2 ÷ [Radius]

### Example values

How the main result changes when **Speed** changes and everything else stays at the example values above:

Speed (m/s)Centripetal force (N)102,000154,500208,0002512,5003018,0004032,000

## Worked example

Inputs — Mass: 1,000 kg; Speed: 20 m/s; Radius: 50 m.

Results — **Centripetal force = 8,000 N**; Centripetal acceleration = 8 m/s².

## FAQ

**Is centrifugal force real?**
It is a fictitious force felt in the rotating frame; from outside, only the centripetal force acts.

**What supplies centripetal force for a car on a bend?**
Friction between the tyres and the road.

**What formula does the Centripetal Force Calculator use?**
F = m v² ÷ r.

**Can I work backwards from the result?**
Yes. Type the result you want into Centripetal force and the calculator finds the matching speed.


## Sources

- [NIST – Fundamental physical constants](https://physics.nist.gov/cuu/Constants/)