Specific Gravity Calculator
Find specific gravity relative to water.
Specific gravity compares a material's density to water.
How the Math Works
Specific gravity is a dimensionless ratio calculated by dividing the density of a substance by the density of a reference material, typically water at 4°C (which has a density of 1000 kg/m³ or 62.4 lb/ft³). When you enter a material's density into this calculator, it automatically divides that value by water's reference density to determine how many times denser (or less dense) your substance is compared to water. A result above 1 means the substance is heavier than water and will sink, while a result below 1 indicates it's lighter and will float.
Practical Applications
To use this calculator, simply enter the density of the material you're analyzing in the appropriate units (kg/m³, g/cm³, or lb/ft³). The calculator handles the conversion and performs the division automatically. For example, if you're testing a metal alloy with a density of 7800 kg/m³, the calculator will compute 7800 ÷ 1000 = 7.8, telling you this material is 7.8 times denser than water. This is essential for quality control in manufacturing, verifying material compositions, or troubleshooting buoyancy issues in engineering projects.
Day-to-Day Use
Specific gravity calculations help you make informed decisions in everyday situations. When swimming or diving, understanding specific gravity explains why some materials float while others sink, helping you choose appropriate equipment. In the kitchen, it can verify if oils or syrups have gone rancid or crystallized by detecting density changes. Hobbyists use it to test battery acid levels, identify unknown minerals, or calculate proper salt concentrations in aquarium systems. Even when packing for travel, knowing specific gravity helps you understand why certain items float in checked luggage while others sink, preventing unexpected weight distribution issues.
Worked example
Aluminum 2700 → SG 2.7.
FAQ
Unitless?
Yes — it's a ratio of densities.