How to use the density converter
- Enter the density in Value.
- In From, choose the unit from your source, such as g/cm³ (g/mL).
- In To, choose the unit you need, such as lb/ft³.
- Read the result. The table shows the same density in every unit, and the swap button reverses the direction.
What it does and when to use it
Density is mass per volume, and almost every field writes it differently. Chemistry and materials data use g/cm³ or g/mL. Engineering tables use kg/m³. American construction and shipping use lb/ft³, machinists use lb/in³, and fuel or paint data is often given in pounds per gallon. This tool moves a figure between all of these.
Typical tasks: turning a material datasheet into lb/in³ to estimate the weight of a machined part, converting a liquid’s g/mL into lb/gal for a shipping form, or checking a concrete or soil density given in lb/ft³. Once you know the density, multiply by the volume to get mass; the volume converter and weight converter help with that step. For how thick a liquid is, rather than how heavy, see the viscosity converter.
How it works
The base unit is kg/m³. Each unit has a factor, and the result is value × from-factor ÷ to-factor. Factors come from the exact pound (0.45359237 kg), inch (0.0254 m), foot (0.3048 m) and gallons:
| Unit | kg/m³ |
|---|---|
| g/cm³, kg/L, t/m³ | 1,000 |
| g/L, mg/cm³ | 1 |
| lb/ft³ | 16.018463374 |
| lb/in³ | 27,679.9047102 |
| oz/in³ | 1,729.99404439 |
| lb/US gal | 119.826427317 |
| lb/UK gal | 99.7763726631 |
| slug/ft³ | 515.378818393 |
Worked examples
Water. 1 g/cm³ = 62.4279605761 lb/ft³, the familiar “62.4 pounds per cubic foot”.
Steel bar stock. 7,850 kg/m³ = 0.283599242201 lb/in³, or about 0.284. Multiply by a part’s volume in cubic inches to get its weight in pounds.
A fuel from a datasheet. 0.74 kg/L = 6.17559929449 lb/US gal, or 7.41658551267 lb per UK gallon.
Limits and tips
- Density changes with temperature and, for gases, with pressure. The converter changes units only; take the density for your actual conditions from a reliable table.
- Bulk density of powders, grain or soil includes air gaps and is lower than the solid material’s density.
- Mass, not weight. All units here are mass per volume. The pound is the pound-mass.
Frequently asked questions
How do I convert g/cm³ to kg/m³?
Are g/cm³, g/mL and kg/L the same?
Why are lb/US gal and lb/UK gal different?
How does specific gravity relate to density?
What is a slug per cubic foot?
Sources
- NIST Guide to the SI, Appendix B.8: Factors for units listed alphabetically — NIST, accessed 2026-10-08
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