Specific Gravity Definition and Values

What Is Specific Gravity?

Measuring specific gravity of beer
Specific gravity is used to determine alcohol content of beer.

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Specific gravity is the ratio of the density of a substance to the density of a reference substance, which is usually water for liquids and air for gases. When water is used, it is at its highest density, which is at 4 °C or 39.2 °F. When air is used, it is most often room temperature air, at 20 °C or 68 °F. Pressure is most often 1 atm. However, conditions of temperature and pressure should be specified when stating a specific density value. Specific gravity is also known as relative density. Specific gravity is a unitless value.

Example Values

The specific gravity of pure water at 4 °C is 1. Other values are:

  • Ethanol: 0.78
  • Urine: 1.003-1.035
  • Blood: 1.060
  • Table salt: 2.17
  • Iron: 7.87
  • Lead: 11.35
  • Osmium: 22.59

Sources

  • Hough, J.S., Briggs, D.E., Stevens, R.; Young, T.W. (1991). Malting and Brewing Science, Vol. II Hopped Wort and Beer. Chapman and Hall. London.