Density Calculator

Enter the mass and volume to calculate density or enter any two values to calculate the remaining value.


  lb / ft³

How to Calculate Density

Density is the measure of a unit’s mass to its volume, or essentially how compact an objects mass is. It is expressed as the unit of mass over the unit of volume, for example lbs/cu ft. To calculate density, divide the mass, or weight, of an object by the volume.

density = mass ÷ volume

Illustration showing the formula to solve density is mass divided by volume.
Illustration demonstrating the formula to find density.

For example, let’s find the density of an object that weighs 5 pounds and has a volume of 2 cubic feet.

density = 5 lbs ÷ 2 cu. ft.
density = 2.5 lbs / cu. ft.

Tip: use our volume calculator to find the volume of an object.

Calculating using Different Units of Measure

The formula above makes the assumption that the resulting density value should be expressed in the same units of measure as mass and volume. It’s possible to to find density of an object when the mass and volume are not in the same units of measure.

The key to finding the density in the desired unit of measure is to convert the mass unit and the volume unit to the right measurements before using the formula above.

For example, let’s find the density of an object in pounds per cubic foot for an object that weighs 80 ounces and has a volume of 3,456 cubic inches.

First, convert the mass to pounds.

mass(oz) = 80 oz
mass(lb) = 80 oz ÷ 16 oz per pound
mass(lb) = 5 lbs

Second, convert the volume to cubic feet.

volume(cu. in.) = 3,456 cu. in.
volume(cu.ft.) = 3,456 cu. in. ÷ 1,728 cu. in. per cu. ft.
volume(cu.ft.) = 2 cu. ft.

Now that that mass and volume are in the correct output unit, enter them in the formula above to find density.

How to Calculate Mass From Density and Volume

Using the formula above, it’s also possible to calculate mass if the density and volume are known. Using algebra, we can rewrite the formula above to allow finding mass.

mass = density × volume

For example, let’s find the mass of an object with a density of 4 pounds per cubic foot and a volume of 3 cubic feet.

mass = 4 lbs / cu. ft. × 3 cu. ft.
mass = 12 lbs

How to Calculate Volume using Mass and Density

It’s also possible to calculate volume if both mass and density are known. Rewriting the original formula like this will allow solving for volume.

volume = mass ÷ density

For example, let’s find the volume of an object with a density of 2 pounds per cubic foot and a mass of 6 pounds.

volume = 6 lbs ÷ 2 lbs / cu. ft.
volume = 3 cu. ft.

Common Material Densities

Densities of common solid, liquid, and gaseous materials.
Material Density
water (at 4 °C) 1.0 g/cm³
isopropyl alcohol 0.786 g/cm³
gasoline 0.77 g/cm³
milk 1.026 g/cm³
aluminum 2.7 g/cm³
brass 8.73 g/cm³
copper 8.96 g/cm³
iron 7.86 g/cm³
steel 8.050 g/cm³
platinum 21.45 g/cm³
air 0.001225 g/cm³
carbon dioxide 0.001977 g/cm³
helium 0.000179 g/cm³

You might also find our water weight calculator and hardwood lumber calculator interesting, which use these same principals of density to determine the weight of these materials.