Density Formula

The density of a material, typically denoted using the Greek symbol ρ, is defined as its mass per unit volume.

Where:

• ρ is the density
• m is the mass
• V is the volume

The calculation of density is quite straightforward. However, it is important to pay special attention to the units used for density calculations. There are many different ways to express density, and not using or converting into the proper units will result in an incorrect value. It is useful to carefully write out whatever values are being worked with, including units, and perform dimensional analysis to ensure that the final result has units of mass/volume.

Note that density is also affected by pressure and temperature. In the case of solids and liquids, the change in density is typically low. However, when regarding gases, density is largely affected by temperature and pressure. An increase in pressure decreases volume, and always increases density. Increases in temperature tend to decrease density since the volume will generally increase. There are exceptions however, such as water's density increasing between 0°C and 4°C.

Common Density Units

Unit	kg/m³
kilogram/cubic meter	SI Unit
kilogram/cubic centimeter	1,000,000
gram/cubic meter [g/m³]	0.001
gram/cubic centimeter	1000
kilogram/liter [kg/L]	1000
gram/liter [g/L]	1
pound/cubic inch [lb/in³]	27,680
pound/cubic foot [lb/ft³]	16.02
pound/cubic yard [lb/yd³]	0.5933
pound/gallon (US)	119.83
pound/gallon (UK)	99.78
ounce/cubic inch [oz/in³]	1,730
ounce/cubic foot [oz/ft³]	1.001
ounce/gallon (US)	7.489
ounce/gallon (UK)	6.236
ton (short)/cubic yard	1,186.6
ton (long)/cubic yard	1,328.9
psi/1000 feet	2.3067

Density of Common Materials

Material	Density in kg/m³
Earth's atmosphere at sea level	1.2
Water at standard temperature and pressure	1,000
The Earth	5,515.3
Iron	7,874
Copper	8,950
Tungsten	19,250
Gold	19,300
Platinum	21,450
Atomic nuclei	2.3×10¹⁷
Black hole	above 1×10¹⁸