Density Converter
Convert between kg/m³, g/cm³, g/mL, lb/ft³, lb/in³, and more density units.
Each step along the axis is ten times the one before — the density units span 4 orders of magnitude, so a straight scale would bunch almost all of them at one end.
Instant insight
Density decides whether something floats
Water is 1 g/cm³, so anything below that floats and anything above sinks. It is also why "heavier than" is meaningless without a volume.
Quote the temperature alongside a density — most substances expand and become less dense as they warm.
Check the direction of the conversion
Going from kg_m3 to g_cm3, the number should get bigger if the new unit is smaller, and smaller if it is bigger.
If it moved the wrong way, the factor has been applied upside down — the most common conversion error there is.
Worked out in your browser — nothing is sent anywhere. Comparison figures are approximate.
Common conversions
Quick Reference — 1 unit = ? Gram per Cubic Centimeter (g/cm³)
| Unit | Value |
|---|---|
| Kilogram per Cubic Meter (kg/m³) | 0.001 |
| Gram per Cubic Centimeter (g/cm³) | 1 |
| Gram per Milliliter (g/mL) | 1 |
| Gram per Liter (g/L) | 0.001 |
| Kilogram per Liter (kg/L) | 1 |
| Pound per Cubic Foot (lb/ft³) | 0.0160185 |
| Pound per Cubic Inch (lb/in³) | 27.6799 |
| Ounce per Cubic Inch (oz/in³) | 1.72999 |
Formula
Multiply by (from factor / to factor)
Everyday Uses
Will it float?
Compare a material's density to water (1 g/cm³) — instant intuition for floating, sinking, and layered liquids.
Material weight estimates
Steel at 7.85 g/cm³ versus aluminum at 2.7 — convert density units to estimate what a part will weigh before machining.
Kitchen science
Recipe densities let you convert "250 g honey" into milliliters when you only have a measuring jug.
Chemistry class
kg/m³, g/cm³, lb/ft³ — homework and textbooks mix them freely; convert without slipping a factor of 1,000.
Material selection
Compare materials quoted in kg/m³ against ones in lb/ft³ when specifying timber, insulation or metal.
Float or sink
Compare a material's density against water's 1,000 kg/m³ to predict whether it floats.
Frequently Asked Questions
What is density and how is it calculated?
Density = Mass ÷ Volume (ρ = m ÷ V). It measures how much mass is packed into a given volume. Common units: g/cm³ (grams per cubic centimetre), kg/m³, g/mL, lb/ft³. Example: a block of aluminium weighing 270 g with a volume of 100 cm³ has a density of 270 ÷ 100 = 2.7 g/cm³. Density determines whether objects float or sink: objects less dense than the surrounding fluid float; denser objects sink.
What is the density of water, and why does it matter as a reference?
Water's density is exactly 1.000 g/cm³ = 1 kg/L = 1,000 kg/m³ at 4°C (its maximum density). At 20°C it is 0.998 g/cm³. This is not a coincidence — the gram was originally defined as the mass of 1 cm³ of water, and the litre as 1 kg of water. Ice is less dense (0.917 g/cm³), which is why it floats. Seawater is denser (~1.025 g/cm³) due to dissolved salts, which is why humans float more easily in the sea than in fresh water.
What are the densities of common materials?
Reference densities (g/cm³): Air: 0.00123. Wood (pine): 0.5–0.6. Ice: 0.917. Water: 1.000. Aluminium: 2.70. Concrete: 2.3–2.5. Glass: 2.5. Titanium: 4.51. Steel: 7.85. Copper: 8.96. Lead: 11.34. Mercury: 13.59 (liquid). Gold: 19.32. Platinum: 21.45. Osmium: 22.59 (densest natural element). Cork (0.12–0.24) floats; steel (7.85) sinks — but a hollow steel ship floats because its average density including interior air is less than water.
What is the difference between density and specific gravity?
Specific gravity (SG) is the ratio of a substance's density to the density of a reference substance (usually water at 4°C for solids/liquids, or air for gases). Since water = 1 g/cm³, a substance with SG = 2.7 has density 2.7 g/cm³. SG is dimensionless (no units). Uses: hydrometers measure SG of liquids (beer brewing: SG ~1.040–1.080; battery acid: SG ~1.265; antifreeze dilution). Oil with SG <1 floats on water; brine with SG >1 sinks.
How does density change with temperature and pressure?
For most liquids and solids: density decreases as temperature increases (thermal expansion). Water is the famous exception — it reaches maximum density at 4°C; both above and below 4°C it expands. This is why ice floats and lakes freeze from the top down (preserving aquatic life). For gases: density is highly sensitive to both temperature and pressure (ideal gas law: ρ ∝ P/T). Hot air is less dense than cold air — this is why hot air balloons rise, why weather fronts form, and why aircraft need longer runways in hot weather ("density altitude").