Density Calculator

About the Density Calculator

Density tells you how much mass is packed into a given volume. It is why a small gold ring feels heavy, why ice floats, and why a tonne of feathers takes up far more room than a tonne of steel. It is one of the first ideas in physics and chemistry, and it is used everywhere from identifying unknown materials to working out the weight of concrete for a foundation or the buoyancy of a boat.

This density calculator works in three directions. It finds density from mass and volume, mass from density and volume, or volume from mass and density. It accepts mass in milligrams, grams, kilograms, pounds or ounces and volume in cubic centimetres, millilitres, litres, cubic metres, cubic inches, cubic feet or US gallons. It shows the density in g/cm³, kg/m³ and lb/ft³, says whether the object would float in water, and names the closest common material.

How to Use the Density Calculator

Choose Find density, Find mass or Find volume.

Enter the two known values and choose their units.

Density can be entered in g/cm³ (the same as g/mL) or kg/m³.

The Formula

  density  ρ = m ÷ V
  mass     m = ρ × V
  volume   V = m ÷ ρ

  1 g/cm³ = 1 g/mL = 1 kg/L = 1,000 kg/m³ ≈ 62.43 lb/ft³

The Greek letter ρ (rho) is the usual symbol for density.

Step-by-Step Examples

Density of a metal block. A block has a volume of 100 cm³ and a mass of 270 g.

  ρ = 270 g ÷ 100 cm³ = 2.7 g/cm³ = 2,700 kg/m³

That matches aluminium.

Mass of gold. Gold has a density of 19.32 g/cm³.

  m = 19.32 g/cm³ × 1 cm³ = 19.32 g

Volume of iron. One kilogram of iron, at 7.87 g/cm³:

  V = 1,000 g ÷ 7.87 g/cm³ = 127.1 cm³

The same kilogram of water would fill 1,000 cm³.

Densities of Common Materials

  Material     g/cm³       Material     g/cm³
  air          0.001225    concrete     2.4
  cork         0.24        glass        2.5
  pine wood    0.5         aluminium    2.7
  petrol       0.74        titanium     4.51
  oak wood     0.75        steel        7.85
  ice          0.917       iron         7.87
  olive oil    0.92        copper       8.96
  water        1.0         silver       10.49
  seawater     1.025       lead         11.34
  mercury      13.53       gold         19.32
                           platinum     21.45

Values are approximate and vary with temperature, and for natural materials such as wood and concrete, with the exact type and moisture.

Floating and Sinking

An object floats in a liquid if its average density is lower than the liquid's, and sinks if it is higher. Water has a density of about 1 g/cm³, so wood, cork and ice float while metals and stone sink. Ice is an unusual case: at 0.917 g/cm³ it is less dense than the liquid water it forms from, because freezing water molecules lock into an open crystal structure. A steel ship floats because its hull encloses a great deal of air, so its average density — steel plus air — is less than that of seawater.

Density and Temperature

Most substances expand as they warm, so their density falls slightly with temperature. Water is densest at about 4 °C, at roughly 0.99997 g/cm³, which is why deep lakes stay near 4 °C at the bottom in winter while ice forms on the surface. Gases change density much more with temperature and pressure than liquids and solids do; air at sea level and 15 °C has a density of about 1.225 kg/m³.

Using Density to Identify a Material

Measuring density is a simple, non-destructive way to check what something is made of. Weigh the object, then measure its volume — for irregular shapes, by the volume of water it displaces when submerged, a method famously credited to Archimedes. A "gold" object with a density well below 19.3 g/cm³ is not solid gold. Alloys and mixtures have densities between those of their ingredients, so density alone cannot always tell materials apart, but it quickly rules many out.

Density, Specific Gravity and Relative Density

Specific gravity, or relative density, compares a material's density with that of water. Because water's density is about 1 g/cm³, specific gravity has the same number as density in g/cm³ but no units: aluminium has a specific gravity of about 2.7, and ice about 0.917. It is used in geology to identify minerals, in brewing and winemaking to track how much sugar has turned into alcohol, and in medicine to test urine concentration. A hydrometer, which floats higher in denser liquids, measures it directly.

Mass Density and Weight Density

In everyday speech people say something is "heavy" when they mean it is dense. Strictly, density is mass per unit volume. Engineers sometimes also use weight density, the weight per unit volume, measured in newtons per cubic metre or pounds-force per cubic foot, which is mass density multiplied by the acceleration due to gravity. On Earth the two are proportional, so a material with double the mass density also has double the weight density. Water, for example, weighs about 9,800 newtons per cubic metre.

Understanding Your Result

The headline is the value you asked for: density, mass or volume.

The density line gives the density in g/cm³, kg/m³ and lb/ft³.

The mass and volume line restates both in grams, kilograms, cubic centimetres and litres.

The compared with water line says whether the object would float or sink.

The material line names the closest common material.

When Should You Use This Calculator?

Use it for physics and chemistry homework.

Use it to estimate the weight of a material from its volume.

Use it to identify an unknown material from a measured mass and volume.

Common Mistakes

Mixing units. Convert kilograms and litres consistently; the calculator does this for you.

Confusing mass and weight. Density uses mass, measured in grams or kilograms.

Measuring the volume of a hollow object. Its average density is lower than the material's.

Forgetting temperature. Densities of liquids and gases change as they warm.