# Force Calculator (F = ma)

> Use Newton’s second law to find force from mass and acceleration, or mass or acceleration from the other two, in N, kN, lbf, kgf, m/s² or g.

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

Newton’s second law says the net force on an object equals its mass times its acceleration. Enter any two of force, mass and acceleration to get the third.

Also called: F = ma calculator, Newton’s second law calculator, Net force calculator.

## Inputs
- Solve for (options: Force, Mass, Acceleration; default force)
- Mass (default 1200)
- Mass unit (options: kilograms (kg), grams (g), tonnes (t), pounds (lb), ounces (oz); default kg)
- Acceleration (default 3)
- Acceleration unit (options: m/s², ft/s², g (9.80665 m/s²); default ms2)
- Net force (default 3600)
- Force unit (options: newtons (N), kilonewtons (kN), pounds-force (lbf), kilograms-force (kgf); default n)

## Results
- Result
- Force
- Force
- Mass
- Acceleration
- Acceleration

## Formula

```
F = m a;  m = F ÷ a;  a = F ÷ m
```

Where:
- F: net force in newtons (1 lbf = 4.4482216152605 N; 1 kgf = 9.80665 N)
- m: mass in kilograms
- a: acceleration in m/s² (1 g = 9.80665 m/s²)

## Worked example
1. F = m × a.
2. F = 1,200 kg × 3 m/s² = 3,600 N.

**Result:** Accelerating a 1,200 kg car at 3 m/s² takes a net force of 3,600 N (about 809 lbf).

## What the result means

The force here is the net (unbalanced) force. To size a motor or brake, add the forces it must also overcome, such as friction, drag or the component of weight on a slope.

## Assumptions and limits
- Constant mass and a single net force along the direction of motion.
- Does not add friction, drag or gravity for you; include them in the net force.

## Questions

### What is a newton?

The force that gives 1 kg an acceleration of 1 m/s². Holding up a 100 g apple takes about 1 N.

### Is weight the same as F = ma?

Weight is the special case where the acceleration is g: W = m g. The Weight Calculator does that for Earth and other planets.

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

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Source: GM¹X CalcVerse — https://calculators.geekmidst.com/calculators/force-mass-acceleration-calculator