Liquid Density Calculator — Temperature Correction, Specific Gravity, and 60+ Liquids

When a liquid is heated, its molecules gain kinetic energy and move faster, pushing each other further apart. This thermal expansion increases the volume occupied by the same number of molecules, reducing the mass per unit volume — and therefore the density. Most liquids expand by 0.05–0.10% per °C, though the rate varies significantly between substances.

Water is a notable exception to the simple rule that "denser when colder." Between 0°C and 4°C, water actually becomes denser as it warms — reaching its maximum density of 999.97 kg/m³ at exactly 3.98°C. Below 4°C, the hydrogen bond network begins to organise into the open hexagonal structure of ice, which is less dense than liquid water. This anomaly has profound ecological consequences: lakes freeze from the top down, preserving liquid water beneath the ice for aquatic life.

In industrial applications, liquid density changes with temperature affect flow measurement, custody transfer, and process control. Petroleum products are bought and sold by volume corrected to a reference temperature of 15°C (API standard) or 20°C (ISO standard). A tank of diesel fuel at 40°C will occupy more volume than the same mass at 15°C — accurate temperature correction is essential for fair commercial measurement. For compressible gas work, use the gas density calculator.

Water is the most important reference liquid; the data below uses IAPWS-IF97 values.

These are common liquid densities at standard reference temperature (20°C), ordered from low to high density.

Specific gravity (SG), also called relative density, is the ratio of a substance's density to the density of a reference substance — almost always water at 4°C (999.97 kg/m³) for liquids and solids. Because it is a ratio, specific gravity is dimensionless. A specific gravity of 1.0 means the substance has the same density as water; greater than 1.0 means denser than water; less than 1.0 means less dense. For the base concept, see what is density.

For practical engineering, water at 15°C (999.1 kg/m³) or 20°C (998.2 kg/m³) is sometimes used as the reference instead of 4°C. Always check which reference temperature is being used when comparing SG values from different sources — the difference is small (< 0.2%) but can matter in precision work.

Specific gravity is widely used in the food and beverage industry (measuring sugar content in wort for brewing, Brix scale for fruit juice), petroleum industry (API gravity for crude oil), and gemology (identifying minerals by their characteristic SG values). A hydrometer — a simple float instrument — directly measures specific gravity by how deep it sinks in a liquid.