About the Density Calculator
This density calculator applies ρ = m ÷ V. Choose which quantity you want — density, mass or volume — enter the other two in whatever units you have (grams, kilograms, pounds; millilitres, litres, cubic feet, gallons), and the answer is converted and shown in several units at once.
Students use it for lab reports and physics problems, makers and engineers use it to estimate the weight of a part from its volume, and cooks and brewers use it to convert between weight and volume for liquids. The results table compares your answer with familiar materials so you can sanity-check whether your object would float in water.
Densities of real materials change with temperature and pressure, particularly for gases and liquids; the reference values are typical figures near room temperature and atmospheric pressure.
How to use the density calculator
- 1Choose whether to solve for density, mass or volume.
- 2Enter the two known values.
- 3Select the unit for each value — they can be mixed, e.g. grams and gallons.
- 4Read the answer in your chosen unit and the SI conversions below it.
- 5Compare with the reference table to check the result is sensible.
Formula and method
Density is mass per unit volume. The calculator converts your mass to kilograms and your volume to cubic metres, applies whichever rearrangement you selected, and then converts the answer back to the units you chose. 1 g/cm³ equals 1 g/mL, 1 kg/L and 1,000 kg/m³.
Specific gravity is the ratio of the density to that of water at about 4 °C (1,000 kg/m³). It has no units: values below 1 float in fresh water and values above 1 sink.
- ρ
- Density (kg/m³ in SI units)
- m
- Mass (kg)
- V
- Volume (m³)
Worked examples
Aluminium block: 540 g, 200 mL
Density = 540 g ÷ 200 cm³ = 2.7 g/cm³, which is 2,700 kg/m³ — exactly the density of aluminium. In imperial units that is about 168.6 lb/ft³.
Mass of 5 US gallons of gasoline
5 US gallons is 18.93 L (0.018927 m³). Multiplying by 740 kg/m³ gives 14.0 kg of fuel, or about 30.9 lb.
Volume of 1 kg of gold
V = m ÷ ρ = 1,000 g ÷ 19.3 g/cm³ = 51.8 cm³ — a kilogram of gold is smaller than a matchbox.
Frequently asked questions
What is the formula for density?+
Density equals mass divided by volume: ρ = m ÷ V. Rearranged, mass = density × volume and volume = mass ÷ density.
What is the density of water?+
Pure water is about 1,000 kg/m³ (1 g/mL) at 4 °C and about 998 kg/m³ at 20 °C. Seawater is slightly denser at roughly 1,025 kg/m³ because of dissolved salt.
How do I convert g/cm³ to kg/m³?+
Multiply by 1,000. For example 2.7 g/cm³ equals 2,700 kg/m³. g/cm³, g/mL and kg/L are all the same number.
How do you find the volume of an irregular object for density?+
Use water displacement: lower the object into a graduated cylinder and read how much the water level rises. The rise in millilitres equals the object’s volume in cubic centimetres.
Why does density change with temperature?+
Most substances expand when heated, so the same mass takes up more volume and the density falls. Gases are affected far more than liquids or solids.