About this calculator
Weight is a force too: on Earth it is mass × 9.81 m/s², shown alongside.
How to use it
- Choose what to find, enter the other values with their units, and read the answer in every common unit.
The formula
F = m × a
- F
- net force
- m
- mass
- a
- acceleration
Worked example
A 1,200 kg car accelerating at 2.5 m/s²
- F = 1,200 × 2.5 = 3,000 N, or 3 kN.
What the result means
1 newton accelerates 1 kg by 1 m/s². 1 kgf, the weight of 1 kg, is 9.81 N.
Assumptions
- The force is the net force, after friction and other forces.
Limitations
- For changing mass, such as rockets, a fuller treatment is needed.
Frequently asked questions
What is 1 newton?
The force that gives 1 kg an acceleration of 1 m/s².
Is weight the same as mass?
No. Mass is in kg; weight is a force, mass × g, in newtons.
What is net force?
The sum of all forces acting, taking directions into account.
Last reviewed on 6 October 2026. Found a mistake? Tell us.