What Is a Newton?
The complete guide to the newton, the SI unit of force, named after Sir Isaac Newton.
Last updated: 2026-03-15
Definition
A newton (symbol: N) is the SI unit of force. It is defined as the force required to accelerate a mass of one kilogram at a rate of one meter per second squared:
1 N = 1 kg × 1 m/s²
This comes directly from Newton's second law of motion: F = ma (force equals mass times acceleration).
Everyday Force Examples
| Force | Newtons (approx.) |
|---|---|
| Weight of a small apple | 1 N |
| Weight of a 1 kg bag of sugar | 9.8 N |
| Weight of a 70 kg person | 686 N |
| Pushing a shopping cart | 20-50 N |
| Average human bite force | 700 N |
| Car engine force at wheels | 2,000-5,000 N |
| Space Shuttle main engine thrust | ~5,250,000 N |
Newton vs Other Force Units
| Unit | Newtons Equivalent |
|---|---|
| 1 pound-force (lbf) | 4.448 N |
| 1 kilogram-force (kgf) | 9.807 N |
| 1 dyne | 0.00001 N |
| 1 kilonewton (kN) | 1,000 N |
Weight vs Mass
Mass (in kg) measures the amount of matter. Weight (in newtons) measures the gravitational force on that matter. On Earth, weight = mass × 9.807 m/s². On the Moon, the same mass weighs about 1/6 as much because lunar gravity is weaker (1.62 m/s²).
History
The newton is named after Sir Isaac Newton (1643-1727), whose laws of motion form the foundation of classical mechanics. Newton's second law (F = ma) directly defines the unit. The newton was adopted by the General Conference on Weights and Measures in 1948.
Convert between force units with our force converter.