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 meters for volume and kilograms per cubic meter for density. Mixing units is the quickest way to get a wrong answer.
- Convert grams to kilograms and liters to cubic meters before entering values.
- One cubic meter is 1000 liters, 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 / ρFrequently asked questions
- How do I calculate density?
- Divide mass by volume. In this calculator that is kilograms divided by cubic meters, giving kg/m³.
- Can I solve for mass or volume instead?
- Yes — pick which of the three to solve for and fill in the other two. Mass is density times volume; volume is mass divided by density.
- What is the density of water?
- About 1000 kg/m³, or 1 g/cm³, at room temperature. That makes it a handy reference point: anything denser sinks in water, anything less dense floats.