Force Calculator
Apply Newton's Second Law (F = m × a) to compute the net force.
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Quick Tip
Enter the mass in kilograms.
About This Tool
Why use Force Calculator?
Newton's second law states that force equals mass times acceleration: F = m × a. Enter a mass in kilograms and an acceleration in m/s² and the result is the net force in newtons.
A 1,500 kg car accelerating at 3 m/s² needs 4,500 N of net force. "Net" matters: this is the resultant after friction, drag and gravity are taken into account, so the engine must produce more than this figure to achieve that acceleration in the real world. One newton is the force that accelerates 1 kg at 1 m/s².
Key Benefits
Newton's second law directly
The same F = ma relationship used throughout mechanics, with no unit juggling.
Works in both directions
Divide a known force by mass to get acceleration, or by acceleration to get mass.
SI units throughout
Kilograms and m/s² give newtons, the units physics questions and engineering specs expect.
How to use Force Calculator
- 1
Enter the mass in kilograms.
- 2
Enter the acceleration in metres per second squared.
- 3
Read the net force in newtons.
- 4
For weight, use 9.81 m/s² as the acceleration — a 70 kg person weighs about 687 N.
Best use cases
Solve F = ma questions in physics homework.
Work out the thrust needed to accelerate a given mass.
Calculate weight as a force from a mass.
Estimate the force involved in a collision from mass and deceleration.
Force Calculator FAQs
What is the formula for force?
F = m × a: force in newtons equals mass in kilograms times acceleration in m/s².
What is the difference between mass and weight?
Mass is the amount of matter, measured in kilograms, and does not change with location. Weight is the force gravity exerts on that mass: 70 kg weighs about 687 N on Earth and around 114 N on the Moon.
What is one newton?
The force needed to accelerate a 1 kg mass at 1 m/s². It is roughly the weight of a 100 g apple on Earth.
Why is it called net force?
Objects usually have several forces acting at once. Only the resultant — the sum of all of them — produces acceleration, so F = ma always refers to that net figure.
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