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Density Calculator: Find Density, Mass or Volume
Choose what you want to find, enter the other two quantities in any of the common units, and get the answer in several units at once, together with the density of everyday materials for comparison.
The density formula
Density is the mass of a material per unit volume: ρ = m ÷ V. Rearranged, mass is m = ρ × V and volume is V = m ÷ ρ. In the SI system density is expressed in kilograms per cubic meter, but laboratories commonly use grams per cubic centimeter, and in the United States pounds per cubic foot is widespread. This calculator converts everything to SI units internally using exact definitions: one pound is 0.45359237 kg, one cubic foot is 0.028316846592 m³, and one US gallon is 3.785411784 liters.
Because the three quantities are tied together, any two give the third. Choose the unknown and the other two boxes appear.
Typical densities for comparison
Densities depend on temperature, purity and composition, so the figures below are round approximate values at room conditions. Use the datasheet of the actual material for real work.
| Material | kg/m³ (approx.) | g/cm³ |
|---|---|---|
| Air at sea level, 15 °C | 1.2 | 0.0012 |
| Water (near 4 °C) | 1,000 | 1.0 |
| Aluminium | 2,700 | 2.7 |
| Steel | 7,850 | 7.85 |
| Copper | 8,960 | 8.96 |
| Lead | 11,340 | 11.34 |
Practical uses
- Ordering material. Multiply a volume by the density to get the mass of sand, soil, liquid or metal you must buy or transport.
- Identifying a material. A measured density near that of a known material can help narrow down what a sample is made of, though alloys and porosity blur the picture.
- Floating and sinking. An object floats in a fluid if its average density is lower than the fluid's. Specific gravity, the ratio to water, makes this easy to see: a value below 1 floats in water.
- Shipping and loading. Compare computed weight with the capacity of containers and vehicles.
Common mistakes and limits
The most frequent error is mixing units, such as grams with cubic meters, which is off by a factor of one million. Another is mistaking weight for mass: this calculator uses mass, and pounds and kilograms are treated as units of mass. Bulk materials such as gravel, soil or grain have a bulk density that includes air gaps, which is lower than the density of the solid particles, so use the bulk figure when you are ordering by volume. Density also changes with temperature, and gases change strongly with pressure. For safety-critical loads such as lifting, structures or vehicles, confirm with the equipment maker or a qualified engineer rather than relying on a rounded estimate.
Worked example
A sample has a mass of 500 g and occupies 250 cm³. What is its density?
Inputs
| Solve for | Density |
|---|---|
| Mass | 500 |
| Mass unit | Grams (g) |
| Volume | 250 |
| Volume unit | Cubic centimeters (cm³ or mL) |
Result
That is 2.0000 g/cm³, or 124.86 lb/ft³.
| Density | 2,000.000 kg/m³ = 2.0000 g/cm³ = 124.856 lb/ft³ |
|---|---|
| Specific gravity (relative to water at 1,000 kg/m³) | 2.0000 |
| Mass | 0.5000 kg = 1.1023 lb |
| Volume | 0.2500 L = 0.000250 m³ = 0.00883 ft³ |
Estimating note: Quantities and ratings here are estimates for planning and learning. Products, local codes and site conditions differ, so check manufacturer data and local regulations, and use a qualified professional for electrical, structural or safety-critical work.
Frequently asked questions
How do I calculate density?
Divide the mass of an object by its volume. For example, 500 grams occupying 250 cubic centimeters has a density of 2 grams per cubic centimeter, which is 2,000 kg/m³.
What is the density of water?
Pure water is about 1,000 kg/m³, or 1 g/cm³, near 4 °C. It is a little lower at higher temperatures, roughly 998 kg/m³ at 20 °C.
What is specific gravity?
Specific gravity is the density of a material divided by the density of water. It has no units, and a value below 1 means the material floats on water.
How do I convert g/cm³ to kg/m³?
Multiply by 1,000. One gram per cubic centimeter equals 1,000 kilograms per cubic meter, so 7.85 g/cm³ for steel is 7,850 kg/m³.
Is mass the same as weight?
No. Mass is the amount of matter, while weight is the force of gravity on it. In everyday use people say weight when they mean mass, and the calculator uses mass.
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References and sources
- NIST: SI units and guidance on mass, volume and density measurement. Link