What this calculator does
A UK unit is 10 mL of pure alcohol, which is deliberately small: it is roughly what an average adult clears in an hour. That makes the unit a useful counting tool and a poor description of an actual drink.
Almost nothing comes in one unit. A pint of 4.5 per cent beer is 2.6 units, and a pint of an 8 per cent beer is 4.5, so a third of the weekly guideline of 14 units can sit in two glasses.
The formula
Multiply the strength as a percentage by the volume in millilitres and divide by 1,000. One unit is 10 mL of pure alcohol, which weighs about 8 grams.
| Term | Meaning |
|---|---|
| UK unit | 10 mL, or about 8 grams, of pure alcohol. |
| ABV | Alcohol by volume, the strength printed on the label. |
| Low-risk guideline | No more than 14 units a week for both men and women, spread over three or more days. |
The inputs explained
| Field | What to enter |
|---|---|
| Drink volume (mL) | Drink volume in millilitres. A UK pint is 568 mL and a large wine glass 250 mL. |
| Alcohol by volume (%) | Alcohol by volume as a percentage, from the label. |
When to use it
Tracking weekly intake
The guideline is stated in units, so drinks have to be converted to count them.
Comparing drinks
A small measure of spirits and a large glass of wine can carry very different unit counts.
Understanding strength creep
Beers and wines have grown stronger over time, so a familiar glass carries more than it used to.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How much does beer strength matter?
The same pint at four strengths.
| Strength | Alcohol units | Pure alcohol content |
|---|---|---|
| 3.5% ABV | 2.0 units | 16 g |
| 4.5% ABV | 2.6 units | 20 g |
| 5.5% ABV | 3.1 units | 25 g |
| 8% ABV | 4.5 units | 36 g |
Questions
Is a unit the same as a standard drink elsewhere?
No, and the differences are large. A UK unit is 8 grams of alcohol, a US standard drink is 14 grams, and Australia uses 10 grams. Unit counts are not transferable between countries.
What does the 14 unit guideline mean?
It is the UK Chief Medical Officers' low-risk guideline, applying equally to men and women, with advice to spread it over three or more days and to have several drink-free days. It describes low risk rather than no risk.
Why is a single drink rarely one unit?
Because the unit was defined as a convenient quantity of alcohol, not as a serving size. Only a single small measure of spirits comes close, at exactly 1.0 unit for 25 mL of 40 per cent spirit.
Does the body clear one unit per hour?
Roughly, on average, but it varies considerably between people and within the same person. It is a useful approximation for planning and not reliable enough to base any decision on, particularly about driving.
For a blood alcohol estimate, see the blood alcohol content calculator. For caffeine clearance by the same decay maths, see the caffeine remaining calculator.