A UK unit of alcohol is 10ml (or 8g) of pure ethanol. It’s a standardized measure designed to help you track how much you’re actually drinking, regardless of whether you’re having beer, wine, or spirits. The concept matters because UK health guidelines, drink-drive limits, and product labels all reference units rather than “drinks.”
How Units Are Calculated
The formula is straightforward: multiply the volume of your drink in millilitres by its ABV (alcohol by volume, the percentage on the label), then divide by 1,000. So a 568ml pint of 4% lager works out to 568 × 4 ÷ 1,000 = 2.3 units. A 250ml large glass of 13% wine is 250 × 13 ÷ 1,000 = 3.25 units.
ABV is the key variable. Two pints that look identical can carry very different unit counts if one is 4% and the other is 5.2%. That second pint contains about 3 units instead of 2.3, nearly a third more alcohol from the same glass.
Common Drinks and Their Unit Counts
Because ABV varies between brands, the numbers below use typical strengths. They’re a useful ballpark, but checking the label on your specific drink will always be more accurate.
- Pint of lower-strength lager (3.6% ABV): about 2 units
- Pint of regular lager or bitter (4% ABV): 2.3 units
- Pint of premium lager (5.2% ABV): about 3 units
- Small glass of wine, 125ml (13% ABV): 1.6 units
- Medium glass of wine, 175ml (13% ABV): 2.3 units
- Large glass of wine, 250ml (13% ABV): 3.25 units
- Single spirit measure, 25ml (40% ABV): 1 unit
- Double spirit measure, 50ml (40% ABV): 2 units
- Bottle of wine, 750ml (13% ABV): about 9.75 units
- Bottle of wine, 750ml (15% ABV): 11.25 units
Notice that a “glass of wine” is not one unit. That’s one of the most common misconceptions. Even a small 125ml glass at 13% is over one and a half units, and many restaurants pour 175ml or 250ml as standard. A single bottle of strong (15%) wine contains more than 11 units, close to an entire week’s recommended limit in one sitting.
Why a “Unit” Isn’t the Same as a “Drink”
The UK unit (8g of pure alcohol) is smaller than the standard drink measures used in many other countries. A US standard drink, for example, contains 14g of pure alcohol, nearly double the UK unit. This means you can’t translate American guidelines directly into UK units, or vice versa, without adjusting for the difference. If you’ve seen advice to “limit yourself to two drinks a day” from a US source, that’s roughly 3.5 UK units, not 2.
The UK unit was deliberately set at a smaller size to give people a more precise way to count. A single 25ml measure of 40% spirits lands at exactly 1 unit, which makes the maths easier for pub measures. Everything else scales from there.
The 14-Unit Weekly Guideline
The UK Chief Medical Officers’ current guidance is the same for men and women: to keep health risks low, drink no more than 14 units per week on a regular basis. That’s roughly six pints of 4% beer, six medium glasses of 13% wine, or fourteen single spirit measures spread across the week.
If you do drink up to 14 units, spreading them over three or more days is safer than concentrating them in one or two sessions. Having several drink-free days each week also gives your liver time to recover. There is no “safe” level of drinking in absolute terms; 14 units is the threshold below which risks remain relatively low.
How Your Body Processes Units
Your liver breaks down alcohol at a roughly fixed rate: about one unit per hour. This rate doesn’t speed up if you drink coffee, eat food after drinking, or take a cold shower. Time is the only thing that clears alcohol from your system. So if you finish your last drink at midnight and you’ve consumed 10 units over the evening, you could still have alcohol in your blood at 10am the next morning.
Several factors affect how strongly alcohol hits you even before your liver gets to work. Food in your stomach, especially fatty or protein-rich food, slows absorption by keeping alcohol in the stomach longer before it reaches the small intestine where most absorption happens. Drinking on an empty stomach does the opposite: alcohol passes straight through. Fatigue, stress, and even altitude can all amplify the effects. Drinks mixed with sugary or carbonated mixers tend to be absorbed faster as well.
These factors change how intoxicated you feel, but they don’t change the number of units you’ve consumed or how long it takes your liver to clear them.
What’s Actually on the Label
You might expect unit counts to be printed on every bottle and can, but UK law doesn’t require it. The only mandatory information on an alcoholic drink is the container volume, the ABV percentage, and allergen warnings. Everything else, including unit counts, calorie information, health warnings, and the 14-unit guideline, is voluntary. Producers can choose to include it, and many do, but there’s no legal obligation.
This means the ABV percentage is your most reliable tool. If unit information isn’t printed on the label, you can always calculate it yourself: volume in ml × ABV ÷ 1,000. Some people find it helpful to use one of the free unit-tracking apps available, which do the maths for you and keep a running weekly total.