Our easy-to-understand guide gives you the facts and advice on alcohol units and measures.
One unit is 10ml or 8g of pure alcohol. Because alcoholic drinks come in different strengths and sizes, units are a way to tell how strong your drink is.
It takes an average adult around an hour to process one unit of alcohol so that there's none left in their bloodstream, although this varies from person to person.
Think you might be drinking too much? Want to know when having enjoying a drink tips over into something you should be concerned about?
Alcohol content is also expressed as a percentage of the whole drink. Look on a bottle of wine or a can of lager and you'll see either a percentage, followed by the abbreviation 'ABV' (alcohol by volume), or sometimes just the word 'vol'. Wine that says '13 ABV' on its label contains 13% pure alcohol.
The alcoholic content in similar types of drinks varies a lot. Some ales are 3.5%. But stronger continental lagers can be 5% or even 6% ABV. Same goes for wine where the ABV of stronger 'new world' wines from South America, South Africa and Australia can exceed 14% ABV, compared to the 13% ABV average of European wines.
This means that just one pint of strong lager or a large glass of wine can contain more than three units of alcohol.
Spirits used to be commonly served in 25ml measures, which are one unit of alcohol, many pubs and bars now serve 35ml or 50ml measures.
Large wine glasses hold 250ml, which is one third of a bottle. It means there can be nearly three units or more in just one glass. So if you have just two or three drinks, you could easily consume a whole bottle of wine – and almost three times the UK Chief Medical Officers' low risk drinking guidelines – without even realising. Smaller glasses are usually 175ml and some pubs serve 125ml.
If you drink wine at home, pour small amounts into your glass.
If you fill glasses to the rim, you'll drink more than you realise. Opt for small (125ml or less) glasses too.
Measure your spirits instead of free pouring them. The Drinkaware unit measure cup is an ideal way to measure spirits, as well as wine and beer.
Try and pour your own drinks. If your partner or host is constantly topping up your half-filled glass, it's hard to keep track of how much alcohol you're drinking.
Try tracking your alcohol consumption each day using our alcohol tracker.
To keep health risks from alcohol to a low level, the UK Chief Medical Officers' (CMO) low risk drinking guidlines advise it is safest not to drink more than 14 units a week on a regular basis.
If you regularly drink as much as 14 units per week, it's best to spread your drinking evenly over three or more days.
If you want to cut down the amount you drink, a good way to achieve this is to have several drink-free days each week.
Read more information on alcohol unit guidelines.
The Chief Medical Officer (CMO) for England recommends against underage drinking stating an 'alcohol-free childhood is the best option'.
Use our Track and Calculate Unit app. It's free and simple to use.
Ask for a small glass of wine. A 125ml glass is around one and a half units of alcohol.
Drink spritzers if you like wine or pints of shandy if you're a lager drinker. You'll still get a large drink, but one that contains less alcohol.
Opt for half pints if you prefer higher strength lager or try a lower strength drink option. You really won't notice the difference.
Alternate alcoholic drinks with soft drinks.
Ask questions. If you're still uncertain about how much you're drinking, ask the bar staff. Do they pour doubles or singles? How big is their large glass of wine?