Density Converter Online – g/cm³, kg/m³, lb/ft³, lb/gal

How to use the Density Converter

Enter a density, using a dot for decimals (0.997, not 0,997).

Choose the unit you have, such as gcm3 (g/cm³), and the unit you need.

Set the significant digits to match the precision of your data.

Copy the converted density.

Density converter for materials and liquids

This density converter switches between ten mass-per-volume units, metric and US customary. Density tells you how much mass fits in a given volume, and it is the bridge between weighing something and measuring its volume.

Metric units that are secretly equal

Several metric density units have identical values, which is worth knowing before you convert anything:

g/cm³ = g/mL = kg/L, because 1 mL is 1 cm³ and 1 kg/L scales both mass and volume by 1000.
kg/m³ = g/L, for the same reason one step down.
Between the two groups the factor is 1000: 1 g/cm³ = 1000 kg/m³.

So a steel density of 7.85 g/cm³ is also 7.85 kg/L and 7850 kg/m³. Milligrams per liter (mg/L) are 1000 times smaller than g/L and are used for dissolved substances in water, where 1 mg/L is roughly one part per million by mass.

Examples

0.997 gcm3  = 997 kgm3           water near 25 °C
0.997 gcm3  = 8.320368239 lbgal
7.85 gcm3   = 490.0594905 lbft3  carbon steel
7.85 gcm3   = 0.2835992422 lbin3
1.225 kgm3  = 0.07647425171 lbft3  sea-level air
19.3 gcm3   = 11.15610777 ozin3

The US customary units are based on the avoirdupois pound and the US gallon, so "lb/gal" here means pounds per US gallon. A figure quoted per imperial gallon would be about 20% higher for the same liquid.

Using density

With density you can move between mass and volume: mass = density × volume, and volume = mass ÷ density. For example, 2 liters of a liquid at 0.92 g/mL has a mass of 1840 g. Convert the volume with the volume converter and the mass with the mass converter so all three quantities share compatible units first.

Typical densities for reference

Handy for a quick sanity check. Values are approximate and vary with temperature and composition; 1 g/cm³ equals about 62.43 lb/ft³.

Material	g/cm³	lb/ft³
Gasoline	≈ 0.74	≈ 46.2
Ice	0.917	57.2
Water (4 °C)	1.000	62.4
Aluminum	2.70	168.6
Copper	8.96	559.4
Lead	11.34	707.9

Worked example: a steel plate of 1 m × 0.5 m × 10 mm has a volume of 0.005 m³. At 7850 kg/m³ it weighs 7850 × 0.005 = 39.25 kg. Keep every length in meters before multiplying, or the result will be off by a power of ten.

Specific gravity

Specific gravity is density relative to water, so it has no unit. Because water is close to 1 g/cm³, the specific gravity of a liquid is numerically very close to its density in g/cm³. The match is not exact: water's density changes with temperature, and standards specify the reference temperature.

Common mistakes

Swapping kg/m³ and g/cm³, which is a factor of 1000.
Mixing US and imperial gallons in lb/gal figures.
Forgetting that gas densities depend strongly on pressure and temperature.

Frequently asked questions

How do I convert g/cm³ to kg/m³?

Multiply by 1000. For example, aluminum at 2.7 g/cm³ is 2700 kg/m³. To go from kg/m³ to g/cm³, divide by 1000.

Is g/mL the same as g/cm³?

Yes. One milliliter is exactly one cubic centimeter, so a density in g/mL has the same number in g/cm³ and in kg/L.

How many pounds per gallon is water?

At about 25 °C water is roughly 0.997 g/cm³, which is about 8.32 pounds per US gallon. Colder water is slightly denser, so you will also see 8.33 or 8.34 quoted.

What is the difference between density and specific gravity?

Density has units, such as kg/m³. Specific gravity is the ratio of a substance’s density to that of water at a reference temperature, so it is unitless and roughly equal to the density in g/cm³.

Density Converter