Specific Gravity Calculator
Calculate specific gravity and relative density with instant buoyancy analysis
Calculate Specific Gravity
Choose whether to calculate specific gravity from density or vice versa
Select a predefined material or choose "Custom Material" to enter your own values
Standard reference is 4°C (39.2°F) when water is densest
Mass per unit volume of the material
Ratio of material density to water density
Specific Gravity Results
Density in Different Units
Additional Information
Formula: SG = ρ_material / ρ_water
Water density at 4°C: 1067.49 kg/m³
Material classification: Unknown
Relative density: Infinity× lighter than water
Example Calculation
Ice Specific Gravity
Material: Ice
Density: 916.7 kg/m³
Water density (4°C): 1000 kg/m³
Calculation
SG = ρ_ice / ρ_water
SG = 916.7 / 1000
SG = 0.9167
Result: Ice floats (SG < 1)
Common Specific Gravities
Liquids
Metals
Other Materials
Buoyancy Guide
SG < 1.0: Floats
Material is less dense than water
SG ≈ 1.0: Neutral
Material has same density as water
SG > 1.0: Sinks
Material is denser than water
Understanding Specific Gravity
What is Specific Gravity?
Specific gravity (also called relative density) is the ratio of a material's density to the density of water at 4°C (39.2°F). It's a dimensionless quantity that tells us how dense a material is compared to water.
Why is it Important?
- •Predicts buoyancy behavior in water
- •Material identification and quality control
- •Engineering design calculations
- •Geology and mining applications
Formula and Calculation
SG = ρ_material / ρ_water
- SG: Specific gravity (dimensionless)
- ρ_material: Density of the material
- ρ_water: Density of water at 4°C (1000 kg/m³)
Key Point: Since specific gravity is a ratio of densities, it's unitless. You get the same result regardless of which density units you use, as long as both densities use the same units.
Practical Applications
Marine Engineering
Ship design, ballast calculations, and determining if materials will float or sink in seawater.
Brewing & Distilling
Measuring alcohol content, sugar concentration, and monitoring fermentation progress.
Geology & Mining
Mineral identification, ore grading, and determining rock composition and porosity.
Temperature Considerations
Specific gravity values depend on temperature because density changes with temperature. Standard reference conditions use water at 4°C (39.2°F) because this is when water reaches its maximum density.
Why 4°C Reference?
- • Water is densest at this temperature
- • Provides consistent reference point
- • Widely accepted international standard
Temperature Effects
- • Higher temperature = lower density
- • Different materials expand differently
- • Always specify reference temperature