# Impulse Calculator

> Find impulse from force and contact time, or from a mass’s change in velocity, and the average force during an impact or push.

Category: Science & engineering · Applies to: Worldwide · Last updated: 2026-10-29
Interactive calculator: https://calculators.geekmidst.com/calculators/impulse-calculator

Impulse is force multiplied by the time it acts, and it equals the change in momentum. Knowing either side gives the other, plus the average force over the contact.

Also called: Impulse–momentum calculator, Average force calculator.

## Inputs
- Calculate from (options: Force and time, Change in velocity; default momentum_change)
- Average force (default 100)
- Force unit (options: newtons (N), kilonewtons (kN), pounds-force (lbf), kilograms-force (kgf); default n)
- Mass (default 0.145)
- Mass unit (options: kilograms (kg), grams (g), tonnes (t), pounds (lb), ounces (oz); default kg)
- Initial velocity (default -40)
- Final velocity (default 50)
- Velocity unit (options: m/s, km/h, mph, ft/s, knots; default ms)
- Contact time (default 1)
- Time unit (options: seconds, milliseconds, minutes, hours; default ms)

## Results
- Impulse
- Impulse
- Average force
- Average force
- Contact time

## Formula

```
J = F Δt = m (v₂ − v₁);  average F = J ÷ Δt
```

Where:
- J: impulse in N·s
- F: average force in N
- Δt: contact time in s
- m: mass in kg
- v₁, v₂: velocities before and after, with sign for direction

## Worked example
1. Change in velocity: 50 − (−40) = 90 m/s, because the ball reverses direction.
2. J = 0.145 × 90 = 13.05 N·s.
3. Average force = 13.05 ÷ 0.001 s = 13,050 N.

**Result:** Reversing a 145 g ball from 40 m/s to 50 m/s in 1 ms takes an impulse of 13.05 N·s, an average force of about 13 kN.

## What the result means

For a fixed change in momentum, a longer contact time means a smaller force. Airbags, crumple zones and bending your knees on landing all work by stretching Δt.

## Assumptions and limits
- Motion along one line; the force shown is the average over the contact time.
- Peak force in a real impact is usually well above the average.

## Questions

### Why does the sign of velocity matter?

A ball that bounces back changes momentum by more than one that stops dead. Enter the incoming velocity as negative and the outgoing as positive to capture the full change.

### Is impulse the same as momentum?

Impulse is the change in momentum, measured in the same units (N·s = kg·m/s).

## Sources
- [BIPM: The International System of Units (SI)](https://www.bipm.org/)

## Related calculators
- [Momentum Calculator](https://calculators.geekmidst.com/calculators/momentum-calculator)
- [Force Calculator (F = ma)](https://calculators.geekmidst.com/calculators/force-mass-acceleration-calculator)
- [Kinetic Energy Calculator](https://calculators.geekmidst.com/calculators/kinetic-energy-calculator)

Source: GM¹X CalcVerse — https://calculators.geekmidst.com/calculators/impulse-calculator