What is an alcohol unit?

• What is a unit?
• Alcohol by volume
• Measures and glass sizes
• Strategies for drinking less at home
• Strategies for drinking less out and about

The government advises that people should not regularly drink more than 3-4 units of alcohol a day for men (equivalent to a pint and a half of 4% beer) and 2-3 units for women (equivalent to a 175 ml glass of wine). 'Regularly' means drinking alcohol every day or most days of the week.

What is a unit?

One unit is 10 ml of pure alcohol. It takes the average adult around an hour to process this so that there's none left in their bloodstream, although this varies from person to person.

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What is a unit of alcohol?

Alcohol by volume

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% ABV, or even 6%. 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 – the upper daily unit guideline limit if you are woman.

Want to know the units in your favourite drinks? Find out here...

Measures and glass sizes

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 government's daily alcohol unit guidelines – without even realising. Smaller glasses are usually 175ml and some pubs serve 125ml.

Strategies for drinking less at home

If you're pouring your own drinks at home, it's easy to drink more alcohol than you realise. Here are some tips to help you keep track:

• 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 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 your host is constantly topping up your half-filled glass, it's hard to keep track of how much alcohol you are drinking. 

More tips for cutting down at home...

Strategies for drinking less out and about

• Use the smartphone version of our MyDrinkaware drink tracking tool. 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 lower strength beer. You really won't notice the difference.
• Alternate alcoholic drinks with soft drinks.
• Ask questions. If you are still uncertain about how much you are drinking, ask the bar staff. Do they pour doubles or singles? How big is their large glass of wine?