Mass Calculator
Find the mass of an object from its density and volume using mass = density × volume. Enter any two of the three quantities and this calculator solves the third, with unit selects covering grams and kilograms, cubic centimeters and cubic feet, and the common density units.
How mass, density, and volume relate
Density is a fixed property of a material — how much mass sits in each unit of volume. Once you know a material’s density, the mass of any piece of it is just that density multiplied by how much space the piece takes up. That is why the same-sized cube of copper is heavier than one of aluminum: copper packs more mass into every cubic centimeter. This calculator is a direct rearrangement of the density equation, so you can start from whichever two numbers you actually have measured.
How it’s calculated
The tool converts your inputs to grams and cubic centimeters, giving density in g/cm³. It then applies mass = ρ × V to find mass, or rearranges to ρ = m ÷ V (density) or V = m ÷ ρ (volume) depending on what you asked to solve. Results are converted back to your chosen mass unit and also shown in grams, kilograms, and pounds.
Assumes a solid, uniform sample. Porous, hollow, or mixed objects have a lower effective density than the bulk material value.
Worked example
A machinist needs the mass of a solid copper block with a volume of 50 cm³. Copper’s density is 8.96 g/cm³, so the mass is 8.96 × 50 = 448 g — that is 0.448 kg, or about 0.988 lb. Swapping the block for aluminum (2.70 g/cm³) would drop the mass to just 135 g.
Common mistakes
- Reading a density table in kg/m³ but entering the number as g/cm³ — they differ by a factor of 1000.
- Using the density of the pure material for a hollow or foamed part, which overstates its mass.
- Confusing volume units; a liter is 1000 cm³, not 100.
- Treating the answer as weight in pounds-force when it is really pounds-mass — the two match only under Earth gravity.
Where it is used
- Estimating shipping weight of manufactured parts before they are made.
- Chemistry and cooking, converting a measured volume of liquid into mass.
- Engineering load calculations that start from geometry and material choice.
- Checking whether a part was made from the claimed material by comparing measured and expected mass.
Frequently asked questions
How do you calculate mass from density and volume?
Multiply density by volume: mass = density × volume (m = ρ × V). For example, a 50 cm³ piece of copper with density 8.96 g/cm³ has a mass of 8.96 × 50 = 448 grams. Keep the units consistent so the volume units cancel.
What is the difference between mass and weight?
Mass is the amount of matter in an object and never changes with location. Weight is the force gravity exerts on that mass, so it changes with gravity — you would weigh about one-sixth as much on the Moon, but your mass would be identical. Scales in kilograms actually infer mass from weight, assuming Earth’s gravity.
Can I enter mass and volume to find density instead?
Yes. Set ‘Solve for’ to Density and the calculator rearranges the formula to ρ = m ÷ V. You can also solve for volume with V = m ÷ ρ. Any one of the three values can be the unknown.
What units does this calculator accept?
Density can be entered in kg/m³, g/cm³, or lb/ft³; volume in cm³, liters, m³, cubic inches, or cubic feet; and mass is returned in grams, kilograms, or pounds. The tool converts everything to a common base internally, so mixed units are fine.
Where do I find a material’s density?
Standard reference tables list densities for common materials — water is about 1000 kg/m³, aluminum 2700, iron 7874, and copper 8960 kg/m³. The density calculator page includes a materials table you can copy values from.