Density calculator (mass, volume and density)
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Result
Calculate density from mass and volume, or the mass or volume of an object from its density. Enter the values in grams, kilograms, pounds or ounces and in cm³, litres, m³, cubic inches, cubic feet or US gallons, and the calculator converts everything to SI units. Pick a common material for its density, or see which material your result matches and whether the object floats in water.
Step-by-step solution
Convert to SI units
Density = mass ÷ volume
Compare with known materials
Key formulas
- Density
- ρ = m/V
- Mass and volume
- m = ρ·V, V = m/ρ
- Specific gravity
- SG = ρ/ρwater, ρwater = 1000 kg/m³ = 1 g/cm³
How to calculate density
- Measure the mass m and the volume V of the object. For an irregular solid, measure the volume as the water it displaces.
- Convert to consistent units, for example kilograms and cubic metres, or grams and cubic centimetres.
- Divide the mass by the volume: ρ = m/V. In SI units the density is in kg/m³; 1 g/cm³ = 1000 kg/m³.
- To find a mass from a density, multiply: m = ρ·V. To find a volume, divide: V = m/ρ.
- Compare with water, about 1000 kg/m³: a solid object that is less dense floats and a denser one sinks.
Questions and answers
What are the units of density?
The SI unit is the kilogram per cubic metre, kg/m³. In chemistry g/cm³ and g/mL are common; they are the same, because 1 mL = 1 cm³. In US engineering lb/ft³ is used: 1 g/cm³ = 62.43 lb/ft³.
What is specific gravity?
The ratio of a density to the density of water, about 1000 kg/m³. It has no unit: steel has a specific gravity of about 7.85, so it is 7.85 times as dense as water.
Does density change with temperature?
Yes, most materials expand when heated, so their density falls. The effect is small for solids and larger for liquids and gases. Water is densest at about 4 °C, which is why ice floats on a lake.
How accurate are the material presets?
They are typical values at about 20 °C. Real alloys, woods, concrete and fuels vary by a few percent or more, so use a measured value or a data sheet when it matters.
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