In Australia, a standard drink is one that contains 10 grams (about 12.5ml) of alcohol. In other countries, this may be different; in the UK, the standard is 8 grams (10ml) of alcohol.

Most beverages are labelled with a percentage of alcohol by volume (e.g. 5%) – so to calculate how many standard drinks a beverage has would involve some simple math. For example:

A 375ml bottle of mid strength beer (2.7% alcohol) = 375 x 0.027 = 10.12ml alcohol
10.12ml / 12.50ml = 0.81 standard drinks.

A 150ml glass of wine (11.5% alcohol) = 180 x 0.115 = 17.25ml alcohol
17.25ml / 12.50ml = 1.38 standard drinks.

Here is a visual representation. 

Whats does 1 unit of alcohol look like