Density Calculator
Calculate the density of any material by entering its mass and volume. Commonly used in chemistry, material science, and engineering to identify substances or check purity.
About this calculator
Density expresses how much mass is packed into a given volume. The formula is ρ = mass / volume, where mass is in grams (g) and volume is in cubic centimetres (cm³), giving density in g/cm³. Pure water at 4 °C has a density of exactly 1 g/cm³, making it a convenient reference point. Objects with density less than a fluid will float; those with greater density will sink — a principle known as Archimedes' principle. Density is an intensive property, meaning it does not change with sample size: a small chip of gold has the same density (19.32 g/cm³) as a gold bar. Chemists use measured density to identify unknown liquids, engineers use it to select lightweight structural materials, and geologists use it to characterise rock and mineral samples.
How to use
You have a metal block with a mass of 540 g and a volume of 20 cm³. Enter mass = 540 g and volume = 20 cm³. The calculator computes ρ = 540 / 20 = 27 g/cm³ — wait, that seems high; let's use realistic numbers. Try mass = 54 g and volume = 20 cm³: ρ = 54 / 20 = 2.7 g/cm³, which matches aluminium perfectly. For a liquid sample of 250 g occupying 200 cm³: ρ = 250 / 200 = 1.25 g/cm³, indicating a denser-than-water solution such as seawater or a sugar syrup.
Frequently asked questions
How do you measure the volume of an irregular solid to find its density?
The displacement method works well for irregular objects. Partially fill a graduated cylinder with water and record the volume, then submerge the object and record the new volume. The difference equals the object's volume in millilitres, which is numerically equal to cm³. Combine that with the object's mass from a scale, and enter both values into the density calculator. This technique was famously used by Archimedes to test whether a crown was pure gold.
What does a density value tell you about whether an object will float?
An object floats in a fluid when its average density is less than the fluid's density. For example, ice (≈ 0.917 g/cm³) floats in water (1.0 g/cm³) because it is less dense. A steel ship floats despite steel being ~7.8 g/cm³ because its hollow hull gives it a large overall volume, reducing its average density below 1.0 g/cm³. Knowing the density lets you predict buoyancy, which is critical in shipbuilding, submarine design, and materials handling.
Why does temperature affect the density of liquids and gases?
Most substances expand when heated, increasing their volume while mass stays constant, so density decreases. Water is a notable exception between 0 °C and 4 °C, where it actually contracts as temperature rises, reaching maximum density at 4 °C. For gases, the ideal gas law shows that density is proportional to pressure and inversely proportional to absolute temperature. Engineers must account for temperature-dependent density when designing fuel systems, HVAC equipment, and chemical reactors.