What's a standard drink?

What is alcohol?

Alcohol (ethanol or ethyl alcohol) is the ingredient found in beer, wine and spirits that can cause drunkenness. Alcohol is formed when yeast ferments (breaks down without oxygen) the carbohydrates or sugars in different food eg, wine is made from the sugar in grapes, beer from the sugar in malted barley (a type of grain), cider from the sugar in apples, vodka from the sugar in potatoes, beets or other plants.

Standard drinks

The standard drinks measure is a simple way for you to work out how much alcohol you are drinking. It measures the amount of pure alcohol in a drink. One standard drink equals 10 grams of pure alcohol.


To work out the number of standard drinks in what you are drinking use this formula:

Amount of drink in litres (Vol) x Percent by volume of alcohol (%) x Density of ethanol at room temperature (0.789)


500ml of beer which is 5 percent alcohol by volume.

0.5 x 5 x 0.789 = 1.97 (approx 2 standard drinks)


If you want to print something out with this information on it, download The Straight Up Guide to Standard Drinks (pdf 463KB), which includes information about the number of standard drinks in different drinks.