g
cm³
Density2 g/cm³
Mass20 g
Volume10 cm³

The formula

ρ=mV\rho = \dfrac{m}{V}
ρ — density (mass per unit volume)
m — mass
V — volume

How it works

Density measures how much mass is packed into a given volume. Because mass, volume and density are tied by one formula, you can enter any two and solve for the third — to identify a material, check if something floats, or convert between weight and size.

FAQ

What units does this use?

It works in grams and cubic centimetres, giving density in g/cm³. That is the same as g/mL for liquids, and 1 g/cm³ equals 1000 kg/m³.

Will an object float in water?

Water has a density of about 1 g/cm³. Anything less dense than that floats; anything denser sinks. Ice floats because it is slightly less dense than liquid water.

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About the density calculator

This calculator finds the density, mass or volume of an object from the other two. Density tells you how heavy something is for its size — a small lump of lead and a large block of foam can weigh the same because their densities are so different. It is one of the most useful properties in science because it stays the same no matter how big the sample is, which makes it a reliable way to identify a material.

How to use it

Pick what you want to find with the “Solve for” menu, then enter the other two values. To find density, type a mass in grams and a volume in cubic centimetres: 20 g in 10 cm³ gives a density of 2 g/cm³. Choose Mass or Volume instead to rearrange the formula — for instance, entering a known density and a volume returns the mass you would expect. Keep the units consistent and the result follows directly.

The formula

Density is mass divided by volume, ρ=mV\rho = \frac{m}{V}, where ρ\rho (rho) is the density, mm is the mass and VV is the volume. Because it is a simple ratio, it rearranges to m=ρVm = \rho V to find mass and V=mρV = \frac{m}{\rho} to find volume. So if you know a material’s density, you can predict how much a given volume will weigh, or how much space a given mass will take up.

Where it is used

Engineers use density to choose lightweight but strong materials, and to work out whether a structure will float or sink. Chemists use it to identify substances and to convert between the mass and volume of a solution. It explains why oil sits on top of water, how hot-air balloons rise, and why a ship made of steel can still float. Geologists, jewellers checking gold purity, and cooks measuring ingredients all rely on the same simple ratio.