Mass Calculator
Enter density and volume in your preferred units. The calculator returns the mass in kilograms, grams, pounds and ounces using m = ρ · V.
Mass (kg)
2.7
- Mass (g)
- 2,700
- Mass (lb)
- 5.95
- Mass (oz)
- 95.24
Mass equals density multiplied by volume: m = ρ·V. The calculator converts your inputs to SI (kg/m³ and m³), multiplies, then expresses the result in kilograms, grams, pounds and ounces. For mixtures, use the bulk density; for porous solids, use apparent density to count void space as part of the volume.
How to use this calculator
Type the material density and pick its unit (g/cm³, kg/m³, g/mL or lb/ft³). Type the volume and pick its unit (cm³, m³, mL, litres, in³, ft³, US or UK gallons). The mass appears immediately in kg, g, lb and oz. The defaults — aluminium at 2.7 g/cm³ in a 1,000 cm³ block — give 2.7 kg.
How the calculation works
Mass is the product of density and volume: m = ρ · V. In SI units, density in kilograms per cubic metre multiplied by volume in cubic metres yields mass in kilograms. The calculator converts whatever units you supplied into SI using NIST conversion factors, multiplies, then expresses the result in four common mass units.
Worked example
A 1-litre bottle of water has density ρ ≈ 1.0 g/cm³ = 1,000 kg/m³ and volume V = 1 L = 0.001 m³. Mass m = 1,000 × 0.001 = 1.0 kg — which is why a litre of water famously weighs a kilogram. An aluminium cube 10 cm on a side has volume 1,000 cm³ = 0.001 m³ and density 2,700 kg/m³, giving mass 2.7 kg.
Frequently asked questions
What's the difference between mass and weight?
Mass is the amount of matter in an object, measured in kilograms or pounds and constant everywhere. Weight is the gravitational force on that mass: W = m·g. On Earth g ≈ 9.81 m/s², so a 1 kg mass weighs about 9.81 N (or 2.2 lbf). This calculator returns mass, not weight.
Where do I find the density of a material?
Common values: water 1.00 g/cm³, ice 0.917, ethanol 0.789, vegetable oil 0.92, milk 1.03. Metals: aluminium 2.70, iron 7.87, copper 8.96, lead 11.34, gold 19.30. Woods (kiln-dried): pine 0.42, oak 0.75. The Engineering Toolbox and CRC Handbook are good lookup sources. Density varies with temperature — use 20 °C values for everyday work.
Why does my g/cm³ figure equal 1,000 × kg/m³?
Unit arithmetic. 1 gram = 10⁻³ kg and 1 cm³ = 10⁻⁶ m³, so 1 g/cm³ = 10⁻³ ÷ 10⁻⁶ = 10³ kg/m³. Water at 1.00 g/cm³ is therefore 1,000 kg/m³ — the cleanest unit conversion in physics.
Does this work for liquids, gases and porous solids?
For liquids and uniform solids, yes. For gases, density depends strongly on temperature and pressure — use the value at the conditions you care about. For porous solids (foam, bread, lung tissue), pick *apparent* density if you treat the air-filled volume as part of the object, or *true* density if you only want the solid skeleton. Mixing the two introduces 10–80 % errors.
What if I have weight instead of mass?
Convert first: m = W / g. If your "weight" is a scale reading in kg or lb, it is already mass (scales are calibrated for Earth gravity). If it is in newtons or pounds-force, divide by 9.80665 m/s² or by 1 lbf/lb to get the underlying mass.
Is the gallon US or imperial?
Both are offered separately. US gallon = 3.785411784 litres (exact). UK (imperial) gallon = 4.54609 litres (exact). They differ by about 20 % — picking the wrong one is the most common source of mass errors when converting from gallons.