Density formula
| Symbol | Quantity | SI unit | Meaning |
|---|---|---|---|
| ρ | Density | kg/m³ | Density of the material |
| m | Mass | kg | Mass of the sample |
| V | Volume | m³ | Volume of the sample |
What is Density?
Density: Density is mass per unit volume, an intrinsic property of a material at a given temperature and pressure.
Density tells you how tightly matter is packed. It is used to identify materials, decide whether objects float, convert between mass and volume, and in nearly every transport equation. For example, thermal diffusivity is k/(ρcₚ).
Specific gravity is density relative to water (≈ 1000 kg/m³). Objects with specific gravity below 1 float in water.
How to use this calculator
- Choose the quantity you want to find in the Calculate menu. It is highlighted as the result field.
- Enter the known values. Scientific notation such as
1.6e-11is accepted. - Select a unit for each value. Units are converted to SI automatically.
- The answer updates as you type. Open Show calculation steps to see the working, or use Copy result to share a link with your inputs.
Worked example
A 270 g metal block has a volume of 100 cm³.
- ρ = 270 / 100 = 2.70 g/cm³, which is aluminium.
Frequently asked questions
How do I measure the volume of an irregular object?
Use water displacement (Archimedes' method). Submerge the object and measure the rise in water level, or measure its apparent weight loss in water.
Does density change with temperature?
Yes. Most materials expand when heated, so density decreases. Water is unusual: it is densest at about 4 °C.