What are the limits?

In technical terms the current legal limits are: 35 micrograms of alcohol in 100 millilitres of breath; 80 milligrams of alcohol in 100 millilitres of blood; 107 milligrams of alcohol in 100 millilitres of urine.
Each alcoholic drink is measured in units of 10 milligrams of alcohol. Drinks are allocated a unit measurement depending on their alcoholic content.
Often people can be putting themselves at risk by driving after consuming alcohol the night before and still having it in their system when they get behind the wheel.

How long does it take?

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

your weight
whether you’re male or female
your age
how quickly or slowly your body turns food into energy (your metabolism)
your stress levels
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.

It’s simply far too difficult to tell exactly how much alcohol will take you over the limit. It’s much better and safer to lay off the drink completely if you do have to drive. You can still have a great night out without alcohol – You can even avoid the dreaded hangover the day after!
To help you keep track of your alcohol intake and how long (on average) it will stay in your system for, you can download and use our mobile phone app as a guide.

Alternative Travel

If you do want to drink you should take into account the alternatives:

Use a taxi – or even better share one!
Use public transport – you’ll even be doing your bit to help the environment!
Designated driver Arrange for someone who is not drinking to drive.


If you are convicted for drink drive offence you will:

Lose your licence for a minimum of one year
You may go to prison for up to six months
You may have to pay a fine of up to £5,000
You may lose your job (15 per cent of those convicted do)
Have a criminal record
Face exceptionally high insurance costs once you get your licence back
Have difficulty hiring a car within ten years of your conviction

For more information about the effects of driving under the influence of alcohol please see the DfT’s Think! Website.

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