What is Specific Gravity?
Specific gravity (SG), also known as relative density, is a dimensionless quantity that compares the density of a substance to the density of a reference material. For liquids and solids, the reference material is almost always pure water at its densest temperature (4°C or 39.2°F). If a substance has a specific gravity less than 1, it will float on water; if it is greater than 1, it will sink.
The Specific Gravity Formula
The mathematical representation of specific gravity is simple: SG = ρsubstance / ρreference. Where 'ρ' (rho) represents the density. Because it is a ratio of two identical units (e.g., kg/m³ divided by kg/m³), the units cancel out, leaving a pure number that helps scientists and engineers compare materials regardless of the measurement system used.
How to Use This Online Calculator
Our Specific Gravity Calculator Online is designed for speed and accuracy. To find the SG of any material:
- Enter the density of the substance you are testing in the first field.
- Select the unit of measurement (kg/m³, g/cm³, or lb/ft³).
- Enter the density of your reference material (water defaults to 1000 kg/m³). Ensure the units match or select the appropriate unit for the reference as well.
- Click "Calculate" to see the result immediately.
Common Applications
Specific gravity is a critical measurement in various fields. In gemology, it helps identify gemstones by comparing their weight to their volume. In brewing and winemaking, hydrometers measure the specific gravity of the liquid to determine sugar content and potential alcohol levels. In civil engineering, it is used to assess the quality and composition of soil and concrete aggregates.
FAQs
Does temperature affect specific gravity? Yes, because density changes with temperature (objects typically expand when heated), the specific gravity will vary slightly depending on the temperature of both the substance and the reference water.
Is specific gravity the same as density? No. Density is the mass per unit volume (e.g., 5 g/cm³), whereas specific gravity is a ratio compared to water (e.g., 5.0).