Density Converter

Density (symbol ρ) is mass divided by volume: ρ = m/V. The SI unit is kilograms per cubic metre (kg/m³), but the gram per cubic centimetre (g/cm³) is widely used in chemistry and materials science because it gives water a conveniently round reference value of 1 g/cm³ at 4 °C. Relative density (specific gravity) is the ratio of a substance's density to that of water, dimensionless and independent of unit system. In the US, density of solids and liquids is often expressed as pounds per cubic foot (lb/ft³) or pounds per cubic inch (lb/in³).

All conversions in this category are computed relative to a single base unit (Kilogram per Cubic Meter) using factors sourced from NIST Special Publication 811 and the BIPM SI Brochure. A shared reference unit keeps the conversion relationships consistent. Converting directly from the original measurement avoids the rounding differences that can accumulate when displayed intermediate results are entered again.

This calculator supports 11 units, including Kilogram per Cubic Meter, Gram per Cubic Centimeter, Gram per Milliliter, Gram per Liter, Kilogram per Liter. Choose the unit shown in your source measurement, then the unit needed for your result.

Units may have alternate spellings or abbreviations. You can search using these names too. Examples include Kilogram per Cubic Meter (kg-m3, also written as kg/m³ or kg/m3), or Gram per Cubic Centimeter (g-cm3, also written as g/cm³ or g/cm3), or Gram per Milliliter (g-ml, also written as g/mL or g/ml).

All density conversions within the SI family are purely multiplicative: you multiply the source value by a fixed conversion factor derived from the ratio of the two unit definitions. Imperial-to-metric conversions use the exact defined equivalences (e.g., 1 inch = 25.4 mm exactly) rather than approximations.

When precision matters, avoid rounding intermediate calculations. The displayed factors and results are rounded for readability, usually to ten significant digits; very large or small values use scientific notation. Use the original measurement for each conversion and round the final answer to match the accuracy of that measurement.

Keep the unit alongside each density value when you copy or share it. Check that the source and target units match your task. If two units have similar names, read their definitions before selecting one.

For a second check, use the worked example and formula on the conversion page. Start from your original value rather than a rounded result from another calculator. If you need to report a specific number of decimal places, round once at the end.