Guide
How to count alcohol units and what the weekly guideline actually means
A plain guide to UK alcohol unit definitions, the 14-unit weekly guideline, and why the clearance estimate is a rough guide, not a driving test.
A unit is a standard measure of pure alcohol
One UK unit is 10ml (8g) of pure alcohol. A pint of standard 4.5% beer contains about 2.3 units. A 175ml glass of 13% wine is about 2.3 units. A 25ml measure of 40% spirits is 1 unit. Stronger beers, larger wine glasses, and double spirits all push the unit count up significantly.
The 14-unit guideline is for regular weekly drinking
The UK Chief Medical Officers advise that men and women should not drink more than 14 units per week regularly — ideally spread across at least three days with alcohol-free days in between. Regularly drinking close to 14 units carries health risks even when spread out; the guideline is a recommended upper limit, not a target.
Clearance estimates are averages, not driving advice
The rough rule of 1 unit per hour is an average across the population and is affected by weight, food, health, and individual metabolism. It is not accurate enough to use as a basis for driving decisions. The safest approach after drinking is not to drive at all until the following morning — and even then, the estimate may be wrong for some people.