Two ways to find mass
This calculator works out mass from whichever pair of measurements you happen to have. Pick a mode and supply its two inputs.
- From density and volume: mass = density × volume, useful when you know the material and its size.
- From force and acceleration: rearranging Newton's second law gives mass = force ÷ acceleration.
Using the result
The mass is reported in kilograms. Because mass is the amount of matter in an object, it stays the same regardless of where the object is, unlike weight, which depends on local gravity.
Keeping units consistent
The result is only correct when the inputs are in SI units, since the formulas assume them.
- Density in kg/m³ and volume in m³ for the density mode.
- Force in newtons and acceleration in m/s² for the dynamics mode.
Caveats and common mistakes
Acceleration cannot be zero in the force mode, since dividing by it is undefined. Take care not to confuse mass (in kilograms) with weight (a force in newtons); to get weight, multiply mass by gravitational acceleration.
Formula
m = ρ·V; m = F / aFrequently asked questions
- What is the difference between mass and weight?
- Mass is how much matter something contains and does not change with location. Weight is the force gravity exerts on that mass, so it differs on the Moon.
- Which mode should I use?
- Use density times volume when you know the material and its size. Use force divided by acceleration when you have measured a force, from Newton’s second law.
- What units does this use?
- Kilograms for mass, kg/m³ for density, cubic meters for volume, newtons for force and m/s² for acceleration.