What this calculator finds

Enter a substance's density and temperature to calculate its specific gravity relative to water density at that temperature. You can also find the substance density from its specific gravity.

Why it matters

• Buoyancy/sinking judgment: SG < 1 floats, SG > 1 sinks in water
• Substance identification: specific gravity is a quick way to assess purity and composition
• Piping/tank design: fluid specific gravity is essential for pump power and pressure drop calculations

Specific Gravity Formula

Specific gravity is found by dividing the substance density by water density at the same temperature. Either 4°C water density (1000 kg/m³) or the water density at the calculation temperature can be used.

Inverse density calculation

Common specific gravity reference values

• Gasoline: 0.70–0.78
• Alcohol (ethanol): 0.79
• Water: 1.000 (reference)
• Seawater: 1.025
• Sodium chloride solution (saturated): 1.20
• Mercury: 13.55

Practical tips

• Specific gravity changes with temperature, so always record the measurement temperature
• Commonly used references are 20°C/4°C (ρ_water = 998.2 kg/m³) or 15.6°C/15.6°C (60°F/60°F)
• Specific gravity is used for density correction in liquid level measurement (buoyancy)

Limitations & cautions

• Specific gravity values vary with reference temperature; the basis must be clearly stated
• Gas specific gravity is typically relative to air (ρ ≈ 1.225 kg/m³); this calculator is for liquids
• Mixture specific gravity varies greatly with composition; experimental measurement is recommended