Force Calculator
Compute force from mass and acceleration (Newton's second law).
Formula
F = m × a
Inputs
- Mass (kg)
- Acceleration (m/s²)
What it does
Newton’s second law: force equals mass times acceleration, F = m × a.
Where it's used
Weights of objects, loads on supports and vehicle acceleration.
How to use it
- Enter the mass in kg.
- Enter the acceleration (9.81 m/s² for weight on Earth).
- Read the force in newtons.
The formula explained
- F
- force, N
- m
- mass, kg
- a
- acceleration, m/s²
Worked example
The weight of a 75 kg person.
Inputs:
- Mass: 75 kg
- Acceleration: 9.81 m/s²
The calculator gives:
- Result: 735.75 N
Tips and common mistakes
- Weight is a force: mass × 9.81.
- 1 kgf ≈ 9.81 N.
- Use the net acceleration after subtracting other forces.
Questions people ask
What is the difference between mass and weight?
Mass, in kilograms, is how much matter something has and is the same everywhere. Weight is the force gravity puts on that mass, in newtons: W = m × g. On the Moon, where g is about 1.62 m/s², the same mass weighs about one sixth as much.
How big is one newton?
One newton accelerates a 1 kg mass by 1 m/s² every second. It is roughly the weight of a small apple of about 100 g.
How do I find the acceleration if I know the force?
Rearrange the law: a = F / m. A 1000 N push on a 500 kg cart gives 2 m/s², ignoring friction. With friction, subtract the friction force first and use what is left.
Related Mechanical & Automotive calculators
Enter your values to get the result with the formula, substituted values and an explanation of each step.