Density Calculator
Calculate density, mass, or volume from any two known values
Choose which two quantities you know, enter the values with their units, and the calculator solves for the third.
Understanding density: the relationship between mass and volume
Density is a fundamental physical property that describes how much mass is packed into a given volume of space. It is defined by the equation: density = mass / volume. Every material has a characteristic density that helps identify it and predict how it behaves. Gold is dense, styrofoam is not. Ice floats on water because it is less dense than liquid water. Understanding density helps in everything from identifying materials to designing structures and packaging products.
This calculator handles all three rearrangements of the density formula. If you know mass and volume, it calculates density. If you know density and volume, it calculates mass. If you know density and mass, it calculates volume. All three modes accept different units for each quantity and convert them to SI units internally before the calculation runs, so you never need to convert manually before entering values.
The reference point for water is 1,000 kg/m³ or equivalently 1 g/cm³. This is the density of pure water at approximately 4 degrees Celsius, where it reaches its maximum density. Materials denser than 1,000 kg/m³ will sink in water; materials less dense will float. Metals typically range from around 2,700 kg/m³ for aluminium up to 19,300 kg/m³ for gold. Wood varies widely but is generally between 400 and 900 kg/m³, which is why wood floats.
Mass units supported are kilograms (kg), grams (g), and pounds (lb). Volume units supported are litres (L), millilitres (mL), cubic metres (m³), and cubic centimetres (cm³). Density output is shown in both kg/m³ and g/cm³, which are the two most commonly used scientific units. Note that g/cm³ and g/mL are equivalent, since one millilitre is defined as one cubic centimetre.
How to use the density calculator
Select which two quantities you already know from the dropdown menu at the top. The form will show only the relevant input fields. Enter the values and select the appropriate units for each. Click Calculate and the result will show the unknown quantity in multiple units along with the values used in the calculation.
If you are working with irregular objects and need to find volume experimentally, the water displacement method is a common approach. Submerge the object in a measuring container of water and note how much the water level rises. That rise in volume equals the volume of the object. Enter that volume here along with the mass to get density.
Common density values for reference
Water is 1,000 kg/m³. Aluminium is about 2,700 kg/m³. Steel is around 7,800 to 8,000 kg/m³. Copper is approximately 8,960 kg/m³. Lead is about 11,340 kg/m³. Gold is 19,320 kg/m³. Air at sea level is approximately 1.225 kg/m³. Petrol (gasoline) is around 720 to 775 kg/m³, which is why it floats on water. Ice is about 917 kg/m³, slightly less than liquid water at 1,000 kg/m³, which explains why ice floats. These reference values help you sanity-check your results and compare materials.
