Density and Specific Gravity Converter

Fluid Mechanics & Material Density Standards

Density is the mass of a substance per unit volume). Specific gravity (relative density) expresses density dimensionless relative to pure water at 4°C).

Common Material Densities

• Air (Sea Level 20°C):

• Gasoline: (SG ~0.74, floats on water)

• Fresh Water:

• Seawater (3.5% Salinity):

• Concrete:

• Structural Steel:

• Liquid Mercury: (SG 13.55)

• Pure Gold:

How to Use This Calculator

Enter your Density Value (e.g. e.g. 1000), From Unit — choose from Kilograms per Cubic Meter (kg/m³, Base SI), Grams per Cubic Centimeter (g/cm³ / g/mL), Kilograms per Liter (kg/L), and To Primary Target Unit — choose from Grams per Cubic Centimeter (g/cm³), Kilograms per Cubic Meter (kg/m³), Pounds per Cubic Foot (lbs/ft³). Results update instantly as you type — adjust any value to compare scenarios.

The Formula

Standard density and specific gravity conversion ratios:/cm^3 to kg/m^3: 1 g/cm^3 = 1 kg/L = 1,000 kg/m^3/ft^3 (pcf) to kg/m^3: 1 lb/ft^3 = 16.018463 kg/m^3/US Gallon: 1 lb/gal = 119.8264 kg/m^3Gravity (SG): SG = (ρ) / (ρ_water) = (ρ (kg/m^3)) / (1,000 kg/m^3)API Gravity: ^= (141.5) / (SG) - 131.5

Worked Example

For example, converting the density of pure fresh water at 4°C: and has a Specific Gravity of 1.0000 (10.0 °API).

Understanding Your Result

Unit conversion precision: round to the same number of significant figures as your original measurement. Converting 6 feet to meters gives 1.8288 m — but if your measurement was approximate (±1 inch), expressing more than 2 decimal places is false precision. For international trade and technical specifications, SI units (meters, kilograms, liters) are the standard. US customary units (feet, pounds, gallons) differ from Imperial UK units: 1 US gallon = 3.785 L vs. 1 UK gallon = 4.546 L.