Can I drink before driving and how long does alcohol stay in the blood? On average, it takes about one hour for your body to break down one 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.
Read more about drinking and alcohol.
How much is one unit?
One unit is equivalent to 10ml or 8g of pure alcohol. There are rough:
- 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 three hours to break down the alcohol.
If you drink one pint of beer, your body takes about two hours to break it down. One pint of strong lager is equivalent to three 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. For more information, see How much alcohol can I drink before driving?
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 three days or more if you drink as much as 14 units a week
Read more about the risks of drinking too much.
- How much alcohol can I drink before driving?
- Risks of drinking too much alcohol
- Alcohol misuse
- Drinking and alcohol