Alcohol Units Calculator
Written by Thierno Sadou Diallo, formula verified per our methodology • Last checked on 9/5/2026
The number of alcohol units is calculated as volume (cl) × alcohol content (%) × 0.8 ÷ 100, with one unit corresponding to 10 g of pure alcohol (the definition used in France and most of Europe). A 50 cl pint of 5% beer represents 2 alcohol units.
Explanation
In France and most European countries, one alcohol unit (also called a 'standard drink') corresponds to 10 grams of pure alcohol, regardless of the drink involved: a half-pint of beer (25 cl at 5%), a glass of wine (10 cl at 12%), and a shot of spirits (3 cl at 40%) at a bar each contain about one alcohol unit, despite very different volumes and alcohol contents — that's precisely the point of this unit of measurement, letting you compare and add up consumption of different drinks on a common basis. The calculation starts from the drink's volume, its alcohol percentage, and the density of ethanol (0.8 gram per milliliter), to get the mass of pure alcohol contained in the glass, then converted into the number of 10 g units. Low-risk consumption guidelines published by French public health authorities recommend, for adults who drink alcohol, not exceeding 10 standard drinks per week, no more than 2 standard drinks per day, and having alcohol-free days — this calculator only measures the content of a single drink, not cumulative consumption tracking. Note that the definition of a standard drink varies by country (see FAQ), so guidelines from different countries aren't directly comparable without adjusting for this difference.
Example: a 50 cl pint of 5% beer
Inputs
Volume: 50 cl. Alcohol content: 5% vol.
Calculation
Units = (50 × 5 × 0.8) ÷ 100 = 200 ÷ 100 = 2.
Result
This pint of beer contains 2 alcohol units, or 20 g of pure alcohol.
Frequently asked questions
Why do a half-pint of beer, a glass of wine, and a shot of spirits all contain about one unit?
Because the volumes served at a bar are historically calibrated to balance volume and alcohol content: a strong spirit (40%) is served in a small volume (3 cl), while a lightly alcoholic beer (5%) is served in a larger volume (25 cl), so that each standard drink delivers a comparable amount of pure alcohol, about 10 g.
What are the low-risk consumption guidelines in France?
French public health authorities recommend, for people who drink alcohol, not exceeding 10 standard drinks per week, no more than 2 standard drinks per day, and having alcohol-free days during the week. These guidelines don't guarantee a total absence of risk, but aim to limit long-term health risks.
Is this unit the same in every country?
No, the definition of a standard alcohol unit varies by country: it corresponds to 10 g of pure alcohol in most European countries (including France), but to 8 g in the United Kingdom and about 14 g in the United States. Comparing consumption guidelines between countries without accounting for this difference can be misleading.