How this density calculator works
Density tells you how much mass is squeezed into a given volume. It is defined by one simple relationship: density = mass ÷ volume, written in symbols as ρ = m / V. Because the three quantities are linked by a single equation, knowing any two of them lets you work out the third.
This calculator converts whatever units you enter into base SI units — kilograms for mass and cubic metres for volume — performs the arithmetic, then converts the answer back into the units you selected. That keeps results consistent even when you mix, say, pounds with millilitres. To solve for mass it uses mass = density × volume; to solve for volume it uses volume = mass / density. Volume and density inputs of zero are rejected when they would force a division by zero.
Common substance densities
These approximate densities are measured at standard conditions (roughly 0–25 °C and ordinary atmospheric pressure). Real values vary with temperature, pressure and purity, so treat them as ballpark references.
| Substance | Approx. density (g/cm³) | kg/m³ |
|---|---|---|
| Air | 0.0012 | 1.2 |
| Ice | 0.92 | 920 |
| Water | 1.0 | 1000 |
| Aluminum | 2.70 | 2700 |
| Iron | 7.87 | 7870 |
| Gold | 19.3 | 19300 |
Reference note: values are approximate and given at standard conditions. Use them for estimates and learning, not for precision engineering or laboratory work.
Frequently asked questions
- What is density?
- Density is how much mass is packed into a given volume. It is defined by the formula density = mass / volume, often written ρ = m / V. A higher density means more mass in the same space.
- How do I calculate density?
- Divide an object's mass by its volume. For example, 200 grams occupying 50 cubic centimetres has a density of 200 / 50 = 4 g/cm³. Make sure mass and volume use consistent units before dividing.
- What units is density in?
- Common density units are grams per cubic centimetre (g/cm³, the same as g/mL), kilograms per cubic metre (kg/m³) used in SI, and pounds per cubic foot (lb/ft³) in imperial work. 1 g/cm³ equals 1000 kg/m³.
- What is the density of water?
- Pure water is about 1.0 g/cm³, which is 1000 kg/m³, near 4 °C. This is why water's density is a convenient reference point: substances denser than 1 g/cm³ sink in water and lighter ones float.
- How do I find mass from density and volume?
- Rearrange the formula to mass = density × volume. For instance, a 2 g/cm³ material filling 10 cm³ has a mass of 2 × 10 = 20 grams. To find volume instead, use volume = mass / density.
- Why do things float?
- An object floats when its average density is less than the density of the fluid around it. If it is denser than the fluid it sinks. This is why ice (about 0.92 g/cm³) floats on water (about 1.0 g/cm³).