A density calculator divides an object’s mass by its volume to find its density. Formula: Density = mass / volume (volume ≠ 0). A 10 g object with a volume of 2 cm³ has a density of 5 g/cm³.
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How to use the density calculator
- Enter the mass.
- Enter the volume in matching units.
- Read the density in mass units per volume unit.
What is the density formula?
Density is mass per unit volume. The density calculator divides the mass you enter by the volume you enter:
- Density ρ = mass ÷ volume
- Mass = density × volume
- Volume = mass ÷ density
The result is in whatever units you used. Grams and cubic centimeters give g/cm³; kilograms and cubic meters give kg/m³, the SI unit. One g/cm³ equals 1,000 kg/m³ and also equals 1 g/mL, because a milliliter is a cubic centimeter.
Density calculator worked example
A block has a mass of 10 g and a volume of 2 cm³. Its density is 10 ÷ 2 = 5 g/cm³. To find a volume, rearrange the formula: 54 g of aluminum, at 2.70 g/cm³, takes up 54 ÷ 2.70 = 20 cm³. To find a mass, multiply: 1 liter (1,000 cm³) of water at about 1 g/cm³ has a mass of about 1 kg.
Densities of common materials
| Material | Density (g/cm³) |
|---|---|
| Air (20 °C, sea level) | 0.0012 |
| Ice | 0.917 |
| Water (4 °C) | 1.000 |
| Aluminum | 2.70 |
| Iron | 7.87 |
| Copper | 8.96 |
| Lead | 11.34 |
| Gold | 19.32 |
Values are typical at room temperature unless noted. Water is densest near 4 °C. Ice is less dense than liquid water, which is why it floats; the USGS notes this is unusual, since most substances are denser as solids.
Measuring mass and volume
Weigh the object on a scale for mass. For a regular shape, measure its dimensions and use a volume formula, such as length × width × height for a box. For an irregular object, use water displacement: put water in a graduated cylinder, note the level, submerge the object and read the new level. The rise is the object’s volume. 1 mL of rise equals 1 cm³.
Density and floating
An object floats in a liquid if its average density is lower than the liquid’s. Wood floats on water, steel sinks, but a steel ship floats because its hull encloses air, lowering its average density. Salt water is denser than fresh water, so things float a little higher in the sea. Comparing a measured density with the table above is also a quick way to check what a material might be: a ring with a density near 19.3 g/cm³ is consistent with gold, while one near 10.5 g/cm³ is closer to silver.
Unit tips
- Keep units consistent: do not mix grams with cubic meters.
- kg/m³ ÷ 1,000 = g/cm³.
- lb/ft³ × 0.016018 = g/cm³; water is about 62.4 lb/ft³.
- Temperature and pressure change density, especially for gases.
The density calculator does not convert units, so convert your mass and volume to matching units first. The density calculator accepts a mass of zero or more and a volume greater than zero, and it also shows specific gravity. The kilogram is the SI base unit of mass, as NIST explains, and the cubic meter is the SI unit of volume.
Specific gravity
Specific gravity is a material’s density divided by the density of water. Because water is about 1 g/cm³, a material’s specific gravity is almost the same number as its density in g/cm³, but without units. Aluminum’s specific gravity is about 2.7, meaning it is 2.7 times as dense as water. Specific gravity is used for minerals, battery acid, brewing and urine tests. Enter your measurements in the density calculator, then divide by 1 to get specific gravity when you use grams and cubic centimeters.
Density of mixtures
For a mixture, total mass divided by total volume gives the average density. Mixing 100 cm³ of a liquid at 1.2 g/cm³ with 100 cm³ at 0.8 g/cm³ gives 200 g in roughly 200 cm³, or about 1.0 g/cm³, although some liquids such as alcohol and water shrink slightly when mixed. The same idea explains why a hollow object can float: add up its mass and its whole enclosed volume, then use the density calculator to compare the average with the liquid.
Related converters and calculators
Related calculators:
- Mass calculator: mass
- Volume calculator: volume
- Unit converter: units
- Scientific calculator: math
Sources
USGS Water Science School: Water density; NIST: SI units – mass.
Questions about this calculator
What is the density formula?
Density = mass ÷ volume.
What is the density of water?
About 1 g/cm³, or 1,000 kg/m³, near 4 °C.
Why does ice float?
Ice is about 0.917 g/cm³, less dense than liquid water.
How do I find the volume of an irregular object?
Use water displacement in a graduated cylinder.
How do I convert kg/m³ to g/cm³?
Divide by 1,000.
Check the assumptions and units before relying on a result. Financial, tax and health estimates do not replace advice for your individual circumstances.
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