How to use the density calculator
- Choose what to solve for: density, mass or volume.
- Enter the mass and pick its unit: kg, g, mg, metric tons, pounds or ounces.
- Enter the volume in m³, liters, cm³ (the same as mL), ft³, in³, US gallons or yd³.
- Enter the density if you are solving for mass or volume.
- The unit next to the quantity you are solving for sets how the answer is shown. The results also list it in other units, the specific gravity and the nearest common material.
The density formula
Density is mass per unit volume. The Greek letter ρ (rho) is the usual symbol:
The SI unit is the kilogram per cubic meter. Chemists often use grams per cubic centimeter, which gives water a density of about 1. Specific gravity is the density divided by the density of water (1,000 kg/m³), so it has no units: steel's specific gravity is about 7.85. The calculator converts every unit to SI first, using the exact definitions of the pound (0.45359237 kg), the inch (2.54 cm) and the US gallon (231 in³).
Worked example
The calculator starts with a sample of 500 g that fills 185 cm³:
- ρ = 500 g ÷ 185 cm³ = 2.703 g/cm³
- In SI units: 2,702.7 kg/m³
- In US units: 2,702.7 ÷ 16.018 = 168.7 lb/ft³
- Specific gravity: 2.703, almost exactly the density of aluminum (2,700 kg/m³)
Switch to mass with the default density of 7.85 g/cm³ (steel) and the same 185 cm³, and the mass is 7.85 × 185 = 1,452 g. Switch to volume and 500 g of steel takes up 500 ÷ 7.85 = 63.69 cm³.
Densities of common materials
| Material | kg/m³ | g/cm³ | lb/ft³ |
|---|---|---|---|
| Air (20 °C, sea level) | 1.204 | 0.0012 | 0.075 |
| Gasoline | 745 | 0.745 | 46.5 |
| Ice | 917 | 0.917 | 57.2 |
| Water (4 °C) | 999.97 | 1.000 | 62.4 |
| Seawater | 1,025 | 1.025 | 64.0 |
| Concrete | 2,400 | 2.40 | 150 |
| Aluminum | 2,700 | 2.70 | 168.6 |
| Steel | 7,850 | 7.85 | 490 |
| Copper | 8,960 | 8.96 | 559 |
| Lead | 11,340 | 11.34 | 708 |
| Gold | 19,300 | 19.30 | 1,205 |
These are typical values near room temperature; the calculator's table lists more. Alloys, woods, fuels and soils vary from sample to sample, so treat a close match as a hint, not proof of what a material is.
Measuring volume and getting it right
For an irregular object, measure volume by water displacement: lower it into a measuring jug or graduated cylinder and read how much the level rises. 185 mL of rise means 185 cm³. Archimedes is said to have used this idea to test a gold crown. The most common mistake is mixing units, such as grams with cubic meters; choose the right unit beside each box instead of converting by hand. Temperature matters for liquids and gases: water is densest at 4 °C, and air at 0 °C is about 7% denser than at 20 °C. For mass from density in more units, or from a weight reading, use the mass calculator.
Frequently asked questions
What is the density of water?
Pure water is about 1,000 kg/m³, or 1 g/cm³, at 4 °C, where it is densest. At room temperature (20 °C) it is 998.2 kg/m³, and seawater is about 1,025 kg/m³ because of the dissolved salt.
How do I convert g/cm³ to kg/m³?
Multiply by 1,000. A cubic meter holds a million cubic centimeters and a kilogram is a thousand grams, so 2.7 g/cm³ is 2,700 kg/m³. To get lb/ft³, multiply g/cm³ by 62.43.
Will an object float in water?
It floats if its average density is less than the water's, about 1 g/cm³ for fresh water. Ice at 0.917 g/cm³ floats with about 92% of its volume under the surface. Steel ships float because their hollow hulls give a low average density.
What is the difference between density and specific gravity?
Density has units, such as kg/m³. Specific gravity is the ratio of a material's density to that of water, so it has none: a specific gravity of 2.7 means 2.7 times as dense as water.
Related calculators
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- Weight Calculator — Weight force W = m × g on Earth, the Moon and the planets, in newtons, pound-force and kilogram-force.
- Molarity Calculator — Molarity from mass and volume, the mass of solute to weigh out, the volume needed, and C₁V₁ = C₂V₂ dilutions.
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