How long does alcohol stay in your blood?

Information written and reviewed by Certified Doctors.

On average, it takes about 1 hour for your body to break down 1 unit of alcohol. However, this can vary, depending on:

  • your weight
  • whether you're male or female
  • your age
  • how quickly or slowly your body turns food into energy (your metabolism)
  • how much food you have eaten
  • the type and strength of the alcohol
  • whether you're taking medication and, if so, what type

It can also take longer if your liver isn't working normally.

How much is 1 unit of alcohol?

1 unit of alcohol is equivalent to 10ml or 8g of pure alcohol. There are roughly:

  • 2.1 units in a standard glass (175ml) of average-strength wine (12%)
  • 3 units in a large glass (250ml) of average-strength wine (12%)
  • 2 units in a pint of low-strength lager, beer or cider (3.6%)
  • 3 units in a pint of higher-strength lager, beer or cider (5.2%)
  • 1 unit in a single measure of spirits (25ml)

Adding up your units

If you drink a large (250ml) glass of wine, your body takes about 3 hours to break down the alcohol.

If you drink 1 pint of beer, your body takes about 2 hours to break it down, 1 pint of strong lager is equivalent to 3 units, so this will take longer.

However, this time can vary, depending on the factors mentioned above.

If you have a few drinks during a night out, it can take many hours for the alcohol to leave your body. The alcohol could still be in your blood the next day.

This means that if you drive the day after an evening of drinking, you could be over the legal alcohol limit.

Know your units

To reduce the risk of harming your health if you drink most weeks:

  • men and women are advised not to regularly drink more than 14 units a week
  • spread your drinking over 3 days or more if you drink as much as 14 units a week
  • it's a good idea to have several alcohol-free days each week

Read more about the risks of drinking too much.

Content supplied by NHS Choices