Force Calculator

How to use the Force Calculator

1. 1Enter the two values you know.
2. 2Pick the units or options from the menus if the force, mass or acceleration tool offers them.
3. 3Read the force, mass or acceleration in the large result box.
4. 4Look at the extra rows for related figures.
5. 5Press Copy result to keep the answer.

When you need the force, mass or acceleration

Engineers use the law to size motors and cables: knowing the mass to move and the acceleration wanted, they can work out the force required. Drivers and cyclists meet it whenever they wonder how hard a car must push to reach a given speed in a given time.

The mass and acceleration mode is the most common, but the other two are just as useful. If you know a rocket's thrust and mass you can find its acceleration, and if you know a force and the acceleration it produced you can find an unknown mass.

How the force, mass or acceleration is worked out

Force = mass × acceleration. So mass = force ÷ acceleration, and acceleration = force ÷ mass. A 75 kg person accelerating at 2 m/s² needs a force of 75 × 2 = 150 N, which is about 15.3 kgf or 33.7 lbf. A 150 N push on a 75 kg trolley gives an acceleration of 2 m/s².

Every answer on this page comes from that one rule, so you can check any result by hand with a calculator. The figures shown underneath, such as other units, are conversions of the same answer.

• Solve for force, mass or acceleration
• Shows newtons, kgf and lbf
• Shows acceleration in g

Mistakes to avoid with force, mass or acceleration

Use kilograms and metres per second squared so that the force comes out in newtons. Remember that the force in the formula is the total, or net, force: if friction or gravity push back, the net force is smaller than the push you apply.

On phone and computer

On a phone, type into the boxes one after another and read the force, mass or acceleration underneath; Copy result puts it on the clipboard for a message or a note. On a computer the inputs sit on the left and the answer on the right, so you can change one figure and watch the force, mass or acceleration move. The force calculator works the same on both. Forces connect to other physics ideas. Momentum Calculator and Kinetic Energy Calculator show what motion adds, Torque Converter changes turning force between units, and Pressure Converter helps when the force acts over an area.

Features

• Use the net force
• Use kg and m/s² for newtons
• Divide, do not multiply, to find mass
• Clear messages when the force, mass or acceleration inputs make no sense
• Copy the result with one tap
• Private: nothing is uploaded

Frequently asked questions