Density converter — kg/m³, g/cm³ and lb/ft³

Material datasheets quote density in whichever unit the industry grew up with: metals in g/cm³, concrete in kg/m³, timber and plastics in lb/ft³. Ten units, one running total.

How to use it

1
Type into any row — say kg/m³ or g/cm³. The results appear immediately, no button needed.
2
Need a combined figure? Fill in two rows, for example kg/m³ and lb/ft³, and they are added together before converting.
3
Set how many digits you want (4–12) and click a result to copy the plain number.

Exact conversion factors

These are the definitions the calculator uses. Nothing here is rounded for convenience — where a value is exact by definition, it says so.

1 g/cm³ = 1000 kg/m³ = 1 kg/l = 1 g/ml exactly
1 lb/ft³ = 16.018463374 kg/m³ · 1 kg/m³ = 0.062427961 lb/ft³
1 lb/in³ = 27 679.9047 kg/m³ · 1 lb per US gallon = 119.826427 kg/m³
Water at 4 °C = 1000 kg/m³ · steel ≈ 7850 · aluminium ≈ 2700 · petrol ≈ 745

Formulakg/m³ = g/cm³ × 1000 · kg/m³ = lb/ft³ × 16.018463374 · lb/ft³ = kg/m³ × 0.062427961

Density conversion table — every unit

One of each unit, converted into the three units people ask for most.

Unit	kg/m³	g/cm³	lb/ft³
1 kg/m³	1 kg/m³	0.001 g/cm³	0.062428 lb/ft³
1 g/cm³	1 000 kg/m³	1 g/cm³	62.428 lb/ft³
1 g/ml	1 000 kg/m³	1 g/cm³	62.428 lb/ft³
1 kg/l	1 000 kg/m³	1 g/cm³	62.428 lb/ft³
1 t/m³	1 000 kg/m³	1 g/cm³	62.428 lb/ft³
1 g/l	1 kg/m³	0.001 g/cm³	0.062428 lb/ft³
1 lb/ft³	16.0185 kg/m³	0.0160185 g/cm³	1 lb/ft³
1 lb/in³	27 679.9 kg/m³	27.6799 g/cm³	1 728 lb/ft³
1 oz/in³	1 729.99 kg/m³	1.72999 g/cm³	108 lb/ft³
1 lb/US gal	119.826 kg/m³	0.119826 g/cm³	7.48052 lb/ft³

kg/m³ → g/cm³, lb/ft³ — quick values

kg/m³	g/cm³	lb/ft³
0.5 kg/m³	0.0005 g/cm³	0.031214 lb/ft³
1 kg/m³	0.001 g/cm³	0.062428 lb/ft³
2 kg/m³	0.002 g/cm³	0.124856 lb/ft³
3 kg/m³	0.003 g/cm³	0.187284 lb/ft³
5 kg/m³	0.005 g/cm³	0.31214 lb/ft³
10 kg/m³	0.01 g/cm³	0.62428 lb/ft³
20 kg/m³	0.02 g/cm³	1.24856 lb/ft³
25 kg/m³	0.025 g/cm³	1.5607 lb/ft³
50 kg/m³	0.05 g/cm³	3.1214 lb/ft³
100 kg/m³	0.1 g/cm³	6.2428 lb/ft³
250 kg/m³	0.25 g/cm³	15.607 lb/ft³
1 000 kg/m³	1 g/cm³	62.428 lb/ft³

How this converter works

Density is mass divided by volume, so the unit is always one mass unit over one volume unit. That is why g/cm³ and kg/l look different but are the same size: a gram in a millilitre is a kilogram in a litre. The converter keeps all four metric spellings on the page because datasheets pick between them almost at random.

The imperial side is where the arithmetic hurts. A pound per cubic foot is 16.018 kg/m³, and a pound per cubic inch is 1728 times bigger again — 27 680 kg/m³. If a figure looks a thousand times off, check which of the two the source meant before trusting it.

Notes and abbreviations

g/cm³, g/ml, kg/l and t/m³ are all the same size — 1000 kg/m³
lb/ft³ — the usual US unit for timber, insulation and concrete
lb/US gal — used for fuels and coatings; the imperial gallon version is 20 percent larger

Questions

What is the density of water?

1000 kg/m³ at 4 °C, which is 1 g/cm³ or 62.428 lb/ft³. It drops slightly as water warms — 997 kg/m³ at 25 °C.

How do I turn density into weight?

Multiply by volume. Two cubic metres of concrete at 2400 kg/m³ weighs 4800 kg — convert that figure on the mass page if you need it in tons.

Is specific gravity the same thing?

Almost. Specific gravity is density divided by the density of water, so a value of 7.85 means 7850 kg/m³.