Drink Drive Limit

What is the drink driving limit?

In the UK the drink driving limit is:

• 35 micrograms of alcohol in 100 millilitres of breath; or
• 80 milligrams of alcohol per 100 millilitres of blood; or
• 107 milligrams of alcohol per 100 millilitres of urine.

How many units can I drink before driving?

The legal drink drive limit cannot be safely converted into a certain number of units, as it depends on a number of factors to include gender, body mass and how quickly your body absorbs alcohol into the blood stream.

Can drinking coffee or having a cold shower help to sober me up?

No, drinking coffee or having a cold shower will not sober you up as this does not remove alcohol from your blood stream.

How long do the effects of alcohol take to wear off?

On average it takes one hour for a healthy liver to process one unit of alcohol. However, it does depend on your body mass, gender and how much food you have consumed. Even if you feel fine after drinking heavily in the evening there is still a high possibility that you will be above the legal limit should you drive the following morning.

What constitutes a unit of alcohol?

One unit of alcohol is 10ml (1cl) by volume or 8g by weight, of pure alcohol.

How do I calculate how many units there are in a drink?

A unit of alcohol is measured by the size (ml) and strength (% alcohol by volume or ABV) of the drink.

The following is a guideline:

Wine
Small Glass (125ml)
12% - 1.5 units
14% - 1.75 units

Standard Glass (175ml)
12% - 2.1 Units
14% - 2.45 Units

Beer
Half Pint
3% - 1 Unit
4% - 1.1 Units
5% - 1.4 Units

330 ml Bottle
3% - 1 Unit
4% - 1.1 Units
5% - 1.7 Units

1 Pint
3% - 2 Units
4% - 2.2 Units
5% - 2.8 Units

Spirits
Single Shot (25ml)
40% - 1 Unit

Double Shot (50 ml)
40% - 2 Units

Port 20% - single shot is 0.5 Unit; double shot is 1 Unit