Convert mass density between kg/m³, g/cm³, g/mL, lb/ft³, lb/in³, lb/gal (US & UK), oz/in³ and slug/ft³ with exact factors.
Enter a density value above to convert.
Reference: water ≈ 1000 kg/m³ = 1 g/cm³.
About this tool
The Density Converter changes a mass-density value between the metric and imperial/US units engineers and scientists use every day: kilograms per cubic metre, grams per cubic centimetre, grams per millilitre, kilograms per litre, grams per litre, pounds per cubic foot, pounds per cubic inch, pounds per US or UK gallon, ounces per cubic inch, and slugs per cubic foot.
Conversion is linear through a single base unit, kilograms per cubic metre (kg/m³). Every unit has a fixed factor expressing how many of that unit make up one kg/m³; the tool divides your value by the source factor to reach the base, then multiplies by the target factor. Key anchors: 1 g/cm³ = 1000 kg/m³, 1 lb/ft³ = 16.0184634 kg/m³, and 1 lb per US gallon = 119.826427 kg/m³. Because the factors are exact constants, the round-trip is stable and repeatable.
A useful reference: pure water at 4 °C is very close to 1000 kg/m³, which equals 1 g/cm³, 1 kg/L and about 62.43 lb/ft³ — handy for sanity-checking a result. All computation happens in your browser, so nothing is uploaded. Choose the from and to units, enter a value, and the converted figure plus its base-unit equivalent appear immediately.
Frequently asked questions
What base unit does the converter use?
All conversions pass through kilograms per cubic metre (kg/m³). The value is divided by the source unit's factor to get kg/m³, then multiplied by the destination unit's factor. The base-unit value is shown alongside the result.
What is the density of water for reference?
Pure water near 4 °C is about 1000 kg/m³, which is 1 g/cm³, 1 g/mL, 1 kg/L, and roughly 62.43 lb/ft³ or 8.345 lb per US gallon. It is the classic benchmark for checking a density conversion.
Do US and UK gallons differ?
Yes. A US gallon is smaller than an Imperial (UK) gallon, so lb/gal (US) and lb/gal (UK) use different factors — 119.83 versus 99.78 kg/m³ per lb/gal. The tool lists both so you can pick the correct one.
Are g/cm³ and g/mL the same?
For practical purposes yes: 1 cm³ equals 1 mL by definition, so g/cm³ and g/mL (and kg/L) are numerically identical and all map to 1000 kg/m³. They are offered separately only for labelling convenience.