Physics
Density from mass and volume
The defining relationship. Divide the mass by the volume it occupies; the units of the answer follow from the units you feed in.
The Formula
rho = m / V
The defining relationship. Divide the mass by the volume it occupies; the units of the answer follow from the units you feed in.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| m | Mass of the sample | mass | Grams or kilograms. Mass, not weight. |
| V | Volume the sample occupies | volume | Cubic centimetres or cubic metres, matching the unit you measured. |
| rho | Density of the material | mass per unit volume | Intensive, so it does not change when you take a larger or smaller piece. |
What Each Symbol Means
mmass
Mass of the sample
Grams or kilograms. Mass, not weight.
Vvolume
Volume the sample occupies
Cubic centimetres or cubic metres, matching the unit you measured.
rhomass per unit volume
Density of the material
Intensive, so it does not change when you take a larger or smaller piece.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to calculate density page applies this equation to a concrete case, shows every intermediate step, and names the mistakes that produce a wrong answer even when the algebra is right.
Where This Formula Appears
This equation is the working core of How To Calculate Density, filed under Science. Every number the guide produces comes from substituting into this one line.