How to use this calculator
- Enter or choose solve for.
- Enter or choose mass unit.
- Enter or choose acceleration unit.
- Enter or choose force unit.
- The result updates as you type. Use Copy result or Share to keep it.
Method
F = m a; m = F ÷ a; a = F ÷ m
- 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
- F = m × a.
- F = 1,200 kg × 3 m/s² = 3,600 N.
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.