How the formula works
Density is mass divided by volume, written as ρ = m / V. Because the three quantities are linked by one equation, knowing any two lets you find the third by rearranging it.
Choose what you want to solve for, then enter the remaining two values. Solving for mass uses m = ρ × V, and solving for volume uses V = m / ρ.
Keeping units consistent
This tool works in SI units: kilograms for mass, cubic metres for volume and kilograms per cubic metre for density. Mixing units is the quickest way to get a wrong answer.
- Convert grams to kilograms and litres to cubic metres before entering values.
- One cubic metre is 1000 litres, and water has a density near 1000 kg/m³.
- If your data is in different units, convert first, then solve.
Where density is used
Density tells you how tightly matter is packed and helps predict how substances behave together.
- Predict whether an object floats or sinks relative to a fluid.
- Identify or compare materials from a measured mass and volume.
- Estimate the weight of a known volume of a liquid or solid.
Common mistakes
Dividing by zero is a frequent slip. Solving for density needs a positive volume, and solving for volume needs a positive density, so those inputs cannot be zero.
Confusing density with weight is another. Density is a property of the material itself, independent of how much of it you have.
Formula
ρ = m / V; m = ρ·V; V = m / ρ