The density of ethanol at 20°C is approximately 0.789 g/cm³.
Density describes how much mass occupies a given volume. At 20°C, one cubic centimetre of pure ethanol has a mass of about 0.789 grams, making ethanol less dense than water, whose density is close to 1.0 g/cm³ at room temperature. The value is commonly reported as 0.789 g/cm³, with more precise tables sometimes giving about 0.7893 g/cm³.
Ethanol’s density depends on temperature because liquids expand as they warm. That is why a density value without a temperature can be incomplete. It also changes when ethanol is mixed with water: alcoholic drinks are generally less dense than pure water, though the exact result depends on alcohol concentration and dissolved sugars.
Ethanol is the alcohol in beer, wine, and spirits, and it is also used as a solvent, fuel, disinfectant ingredient, and laboratory reagent. Its relatively low density helps distinguish it from water in calculations, but density alone cannot identify an unknown liquid safely.
A common mistake is confusing density with specific gravity. Specific gravity is a ratio relative to a reference substance and has no units; 0.789 g/cm³ is an absolute density measurement.