'''Specific Gravity (SG)''' is a measure of the relative density of one material compared to another. For brewing, the reference material is water, so the specific gravity of [[wort]] or beer is simply the density of the liquid divided by the density of water. This results in a dimensionless number, which by brewing convention is usually listed to three decimal places. For example, water would have a specific gravity of 1.000, while an unfermented wort might have a specific gravity of 1.048. Finished beer would typically have a specific gravity in the 1.005-1.015 range. The specific gravity measure is somewhat ambiguous, since the density of water does vary with temperature, but by convention specific gravity in brewing is typically measured by a [[hydrometer]] calibrated to 60 F.