Solve F = ma, weigh anything on Earth, the Moon, Mars or Jupiter, or work out net force and the acceleration it produces.
1 newton is the force that accelerates 1 kg at 1 m/s². Weight is a force, so it changes with gravity while mass does not.
Force
—How to use this tool
Force from mass and acceleration, weight on a body, or net force.
Mass in kilograms — it never changes, wherever the object is.
An acceleration, a planet or moon, or the applied and resisting forces.
Results come in newtons, with pounds-force alongside.
Formula & worked example
A 10 kg mass accelerated at 5 m/s² needs 10 × 5 = 50 N. The same 10 kg on Earth weighs 10 × 9.807 = 98.07 N, but on the Moon only 10 × 1.62 = 16.2 N. With 100 N applied and 30 N resisting, the net force on a 10 kg mass is 70 N and its acceleration is 7 m/s².
Limitations — read this before you rely on it
Gravity values are standard surface averages (Earth 9.807, Moon 1.62, Mars 3.71, Jupiter 24.79, Sun 274 m/s²); local gravity varies slightly. This calculator treats motion in a straight line with constant forces — real systems with changing friction or drag need more detail.
Frequently asked questions
The force that accelerates 1 kg at 1 m/s². Push a 1 kg book so it speeds up by 1 m/s every second and you are applying about 1 N.
No. Mass (kg) is how much stuff there is and never changes; weight (N) is the pull of gravity on it and changes from planet to planet.
Because resistance beats the applied push — the object slows down, or accelerates in the opposite direction.
Multiply by 0.224809. 50 N is about 11.24 lbf. Pounds here are a force, not a mass.
Only as a single resisting force you enter. It does not model friction coefficients, air drag or changing forces.