What is a unit that measures force?

A unit that measures force is the newton. The newton, symbol N, is the derived unit of force in the International System of Units (SI). One newton is defined as the force needed to accelerate a one-kilogram mass by one metre per second squared, written as 1 kg·m/s².

The unit honors English physicist and mathematician Isaac Newton, whose laws of motion established the relationship between force, mass, and acceleration. Newton’s second law is commonly expressed as F = ma: force equals mass multiplied by acceleration. This equation explains why the same push produces different accelerations in objects of different masses.

The newton became the official name for the MKS unit of force in 1948, after international standards work in 1946 had formalized its underlying definition. A common mix-up is confusing force with mass: kilograms measure mass, while newtons measure force. Weight is a force too, so a 1-kilogram object weighs about 9.81 newtons at Earth’s average surface gravity.