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What Is Specific Gravity? How Do You Measure It?

Specific gravity is also called relative density. It’s used to define the weight or density of a substance as compared to the density of an equal volume of a reference substance at a specified temperature.

Specific gravity for liquids is almost always measured with reference point to water with the temperature at 4 °C or 39.2 °F.

Specific gravity for gases is almost always measured in the reference to air at room temperature of 20 °C or 68 °F.

Specific Gravity Is A Measurement

Specific gravity is the ratio of the density of a substance to the density of a reference substance. (source 🗗)

In most of the cases the reference substance is water for liquids or air for gases. Specific gravity represents a ratio and is therefore dimensionless. (source 🗗)

For example the density of sampled liquid / density of water = specific gravity. (source 🗗)

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Sara Niemelä

co-founder Care Omnia, Head Content Creator


I’m a wife and a mother of three. I enjoy the outdoors, cooking, and spending time with my family. Nutrition is my passion. I have spent thousands upon thousands of hours reading, analyzing, categorizing and comparing research studies. Nutrition is the foundation you build a healthy and fulfilling life upon!