Why this matters
Density — mass per unit volume — is expressed in wildly different units depending on your field. A materials engineer specifies aluminum at 2,700 kg/m3, a chemist writes the same value as 2.7 g/cm3, and a hydrologist working in US customary units needs 168.6 lb/ft3. Trying to convert between these mentally is error-prone because the conversions involve both mass and volume factors multiplied together. One wrong factor and your specific gravity calculation puts iron lighter than water.
This converter pivots everything through kg/m3 as the canonical unit and converts to all seven supported outputs simultaneously: kg/m3, g/L, g/cm3, g/mL, lb/ft3, lb/in3, and lb/US gallon. Enter once, see every equivalent with copy buttons for each. The dual-label approach (g/cm3 and g/mL are numerically identical but contextually different) ensures you get the format your audience or specification sheet expects without a second tool.
Supported units
| Unit | System | Water at 4 C |
|---|---|---|
| kg/m3 | SI | 1000 |
| g/cm3 | CGS | 1.0 |
| g/mL | CGS | 1.0 |
| g/L | Metric | 1000 |
| lb/ft3 | Imperial | 62.43 |
| lb/in3 | Imperial | 0.0361 |
| lb/US gal | US Customary | 8.345 |
How to use it
Enter a density value in any of the seven supported units.
Select the source unit from the dropdown.
Read all equivalent density values instantly, with a copy button next to each.
Testing your result
Start with water: enter 1.0 and select g/cm3 as the source. Confirm that kg/m3 reads 1000, lb/ft3 reads approximately 62.43, and g/mL reads 1.0. Then test a heavy material like gold (19.3 g/cm3) and verify that lb/in3 comes out to roughly 0.698. Finally, convert from imperial to metric by entering 62.43 lb/ft3 and confirming the tool returns 1000 kg/m3, which should round-trip back to the original water density.
Common mistakes
Confusing mass with weight — lb is a unit of force, but in this context lb/ft3 implicitly means pound-mass per cubic foot.
Assuming g/cm3 and g/mL always mean the same thing in context — numerically identical, but one is standard for solids and the other for liquids.
Forgetting that water density changes with temperature: 1.0 g/cm3 is exact only at approximately 4 degrees Celsius, and 0.998 at room temperature.
Edge cases and limitations
The converter works with the fixed conversion factors between these units and does not account for temperature-dependent density variations. For precise scientific work, you need temperature-corrected density tables. The tool handles zero and negative inputs without error but density below zero has no physical meaning. All conversion runs in your browser with no data leaving your device.
Real-world use cases
A metallurgist converting a steel density specification from kg/m3 to lb/ft3 for a US-based fabrication team.
A home brewer checking whether a wort's specific gravity (essentially density relative to water) matches the target range for their beer style.
A shipping logistics specialist calculating volumetric weight by converting cargo density to lb/ft3 for freight cost estimation.
Frequently asked questions
Q: What is the density of water?
A: 1 g/cm3 = 1000 kg/m3 at 4 degrees Celsius (maximum density). At room temperature (20 C), water is 0.998 g/cm3. Ice is approximately 0.917 g/cm3, which is why it floats.
Q: What is specific gravity?
A: Ratio of a substance's density to water's density. It is dimensionless. Gold has SG 19.3, aluminum 2.7, mercury 13.6. SG above 1 sinks in water; below 1 floats.
Q: What is the densest common material?
A: Osmium at 22.59 g/cm3, roughly twice as dense as lead (11.34). Gold is 19.3, platinum 21.45. Depleted uranium is 19.1.
Q: Why use kg/m3 vs g/cm3?
A: kg/m3 is the SI unit (water = 1000). g/cm3 is more intuitive for solids and liquids (water = 1). Pick what your audience expects.
Q: Can I convert specific gravity with this tool?
A: Since specific gravity is numerically equal to g/cm3 for materials denser than water, you can enter the SG value as g/cm3 and read all other unit equivalents.
Start using it now
Convert density values across seven units with the Density Converter. For related unit conversions, try the Weight Converter and Volume Converter. If you are working with fluid dynamics, the Pressure Converter complements density for calculating force per unit area.
