Calculate force, mass or acceleration with Newton’s second law.
Calculated locally in your browser.
How is force calculated with Newton's second law?
Force = mass × acceleration (F = ma), so mass = F ÷ a and acceleration = F ÷ m. Enter any two of force, mass and acceleration to find the third. For example, a 10 kg mass accelerating at 2 m/s² experiences a 20 N force. Use SI units: newtons, kilograms and metres per second squared.
Understanding your result
Use SI units: newtons, kilograms and metres per second squared.
Formula and method
Force = mass × acceleration. So mass = F ÷ a and acceleration = F ÷ m.
Assumptions and limitations
It applies Newton's second law, F equals ma, giving the net force on an object. It assumes SI units and a single resultant force, and does not resolve several forces acting at different angles, account for friction separately or handle relativistic speeds.
Worked example
A 10 kg mass accelerating at 2 m/s² experiences a 20 N force.
How to use this tool
- Enter any two values.
- Leave the unknown blank.
- Press Calculate.
Common mistakes to avoid
- Using grams instead of kilograms for mass.
About the Force Calculator (F = ma)
Apply Newton’s second law, F = ma, to find force, mass or acceleration from the other two.
Who should use this tool
Physics students applying Newton's second law, teachers setting mechanics problems, and engineers making quick estimates who know two of force, mass and acceleration and want the third derived from F equals ma without rearranging the equation by hand.
Benefits
- Finds force, mass or acceleration from the other two
- Applies Newton's second law directly with no rearranging
- Uses clear SI units of newtons, kilograms and metres per second squared
- Runs instantly in the browser with no sign-up
Practical use cases
- Solving a mechanics problem for a physics class
- Estimating the force needed to accelerate a mass
- Finding an object's acceleration under a known force
- Checking a homework answer involving F equals ma
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Frequently asked questions
What is one newton?
One newton is the force that accelerates a 1 kg mass at 1 m/s².
What is one newton of force?
One newton is the force needed to accelerate a mass of one kilogram at one metre per second squared. It is the SI unit of force. So a 10 kilogram mass accelerating at 2 metres per second squared experiences 20 newtons, since force is mass times acceleration.
Does this force include the effect of gravity?
The tool gives the net force from whatever mass and acceleration you enter. To find weight, the force of gravity on a mass, use gravitational acceleration of about 9.81 metres per second squared as your acceleration value. Otherwise it simply multiplies the two figures you provide.