Calculator
Alcohol units calculator
How many units are in this beer?
A unit is a fixed quantity of pure alcohol — 10ml, or 8g, in the UK definition — so the same drink can be very different numbers of units depending on how big the glass is. This is the arithmetic most people get wrong, and they usually get it wrong in the direction of underestimating.
The two variables are strength and volume, and volume is the one that catches people out: a pint of 5.2% beer is nearly three units, where a 330ml bottle of the same beer is under two. Knowing the figure matters because official low-risk drinking guidance is expressed in units per week, and it cannot be followed without being able to count them.
Result
- Alcohol units2.8 units
- Per serving2.8 units
- Pure alcohol22.4 g
- US standard drinks1.6
- Australian standard drinks2.2
Working
Units = (volume in ml × ABV%) ÷ 1000
| Step | Expression | Value |
|---|---|---|
| Alcohol volume | 568 × 5% ÷ 100 | 28.4 ml ethanol |
| Units per serving | ml ethanol ÷ 10 | 2.84 units |
| Total | 2.84 × 1 | 2.8 units |
| As mass | ml ethanol × 0.789 g/ml | 22.4 g |
What it means
The UK Chief Medical Officers’ guidance is framed in units per week. This calculator reports what a given drink contains so that guidance can be applied; it makes no recommendation of its own.
Worked example
The example above starts from these values. It is rendered on the server, so the formula, assumptions and limitations are all present whether or not you change anything.
- Result2.8 units
- Per serving2.8 units
- Pure alcohol22.4 g
- US standard drinks1.6
- Australian standard drinks2.2
Inputs
| Volume per serving | 568 ml |
|---|---|
| Strength | 5% ABV |
| Servings | 1 |
How it is calculated
Units = (volume in ml × ABV%) ÷ 1000
What each term means
| volume | Serving size in millilitres — an imperial pint is 568 ml |
|---|---|
| ABV% | Alcohol by volume, as printed on the label |
| 1000 | Converts to UK units, each defined as 10 ml of pure ethanol |
Step by step
| Step | Expression | Value |
|---|---|---|
| Alcohol volume | 568 × 5% ÷ 100 | 28.4 ml ethanol |
| Units per serving | ml ethanol ÷ 10 | 2.84 units |
| Total | 2.84 × 1 | 2.8 units |
| As mass | ml ethanol × 0.789 g/ml | 22.4 g |
What this assumes
- The ABV printed on the label is accurate. Labelling tolerances permit a margin, so the true figure may differ slightly.
- The serving is the full stated volume.
Where it stops being reliable
- A UK unit is 10 ml of pure ethanol. Other countries define standard drinks differently — 14 g in the United States, 10 g in Australia — so guidelines expressed in "drinks" do not translate directly.
- This describes what is in the glass. It says nothing about how alcohol affects any individual.
What the number means
The UK Chief Medical Officers’ guidance is framed in units per week. This calculator reports what a given drink contains so that guidance can be applied; it makes no recommendation of its own.
Definition. The figure is fixed by a published definition rather than measured, so the calculation is arithmetic applied to a stated convention.
Sources: UK Chief Medical Officers’ definition of the alcohol unit.
This shows how much alcohol is in a drink. It cannot tell you how alcohol affects you, and it must not be used to judge whether you are fit to drive. Drink-drive limits are enforced on measured blood or breath alcohol, and how quickly a person processes alcohol varies with body composition, food, medication and other factors no calculator can see.