Alcohol units turn vague 'how much did I drink?' into a countable number — and that number is what guidelines are built on. It's also the honest way to compare a craft IPA against a standard lager.
How units work
A unit is a fixed amount of pure alcohol: 10 ml. Because drinks vary wildly in both volume and strength, counting 'drinks' is unreliable — a strong pint can hold three units while a small beer holds one. Volume times ABV gives the true figure.
Units vs standard drinks
The US frames the same idea as a standard drink of 14 g of alcohol, roughly 1.77 UK units. Whichever system your country uses, the principle is identical: it's the pure alcohol content that counts.
Reading the guidelines
Low-risk guidance, like the UK's 14 units a week, exists to put the math in context. Comparing your evening's total against that benchmark turns a drinking habit into a number you can actually evaluate.
Frequently asked questions
A 175 ml glass of wine at 12.5% ABV is about 2.2 units. Larger glasses and higher ABV push it up quickly.
A UK unit is 10 ml of pure alcohol; a US standard drink is 14 g (about 17.7 ml). So 1 standard drink ≈ 1.77 units.
Alcohol itself provides about 7 kcal per gram. This calculator estimates alcohol calories before any mixers, which add more.