Density Converter
Hydrometers read specific gravity; lab reports use g/cm³ or kg/m³; US datasheets use lb/ft³. Water is 1,000 kg/m³ — or 1 g/cm³, or 62.4 lb/ft³, or SG 1.0. One wrong unit and your buoyancy calc or mix ratio is off.
Quick reference: Water = 1,000 kg/m³ = 1 g/cm³ = 1 g/mL = 62.4 lb/ft³ = specific gravity 1.0. Use this as the anchor; convert any material density below.
All Converters
Quick Reference: Most Searched Density Conversions
Real-World Density Scale
How these numbers relate to everyday lifeWho Uses Density Conversions?
Chemicals & process
Reaction recipes and safety data sheets use g/cm³, kg/m³, or lb/gal. Pumps and pipes are sized by density. Wrong unit leads to wrong flow or overpressure.
Sulfuric acid ~1.84 g/cm³ = 1,840 kg/m³ = 15.3 lb/gal (US). Use correct density for dosing.
Buoyancy & marine
Archimedes: displaced volume × fluid density = buoyant force. Seawater ~1,025 kg/m³; fresh water 1,000. US naval and civil engineering often use lb/ft³; convert for consistent formulas.
1 m³ seawater weighs ~1,025 kg. In lb/ft³: 1,025 kg/m³ = 64.0 lb/ft³ (approx).
Metals & materials
Data sheets give density in g/cm³ (metric) or lb/in³ (US). Weight-per-length (e.g. lb/ft for beam) needs density and cross-section; wrong unit gives wrong weight.
Steel 7.85 g/cm³ = 0.284 lb/in³. A 1 in² × 1 ft steel bar: 0.284 × 12 = 3.4 lb.
Food & beverage
Brix, Plato, and specific gravity (SG) relate to density for sugars and alcohol. Hydrometers read SG; recipes may want g/mL or kg/m³. Converting avoids wrong strength or dosage.
SG 1.050 ≈ 1,050 kg/m³ (sugar solution). 1.0 = water. Alcohol content calculations use density tables.
Mining & aggregates
Ore and rock density in kg/m³ or lb/ft³; specific gravity (relative to water) is common in mining. Tonnage from volume needs correct density and unit.
Ore SG 2.7 = 2,700 kg/m³. 100 m³ ore = 270 tonnes (metric).
Did You Know?
Specific gravity (SG) is density divided by the density of water at 4°C (1,000 kg/m³). So SG has no unit: water = 1.0, gold ≈ 19.3. Hydrometers read SG directly.
Source: ASTM
The pound per cubic foot (lb/ft³) is still widely used in US civil and mechanical engineering. 1 lb/ft³ = 16.0185 kg/m³. Water ≈ 62.43 lb/ft³.
Source: NIST
Water reaches its maximum density at about 4°C (1,000 kg/m³). Ice is less dense (~917 kg/m³), which is why ice floats and lakes freeze from the top.
Source: IAPWS
Common Mistakes to Avoid
Treating specific gravity and density as the same number in different units
SG is dimensionless (density / density of water). So SG 1.5 = 1,500 kg/m³ = 1.5 g/cm³. Do not use "1.5 SG" as 1.5 kg/m³.
Using lb/ft³ and kg/m³ without converting in the same formula
1 lb/ft³ = 16.0185 kg/m³. In F = ρ × V × g, use consistent units: e.g. ρ in kg/m³, V in m³, g in m/s² to get force in N.
Assuming g/mL and g/cm³ are different
They are the same: 1 g/cm³ = 1 g/mL. So water = 1 g/cm³ = 1 g/mL. Chemistry often uses g/mL; physics uses kg/m³.
Key relationships
SI and metric
- 1 g/cm³ = 1,000 kg/m³ = 1 g/mL
- 1 kg/m³ = 0.001 g/cm³
US and specific gravity
- 1 lb/ft³ = 16.0185 kg/m³
- SG 1.0 = 1,000 kg/m³ (water)
NIST factors. Density varies with temperature and pressure.