The amount of alcohol you can drink before you get behind a wheel of a car.


In England, Wales and Northern Ireland the drink drive limit is:

  • 80 milligrammes of alcohol per 100 millilitres of blood
  • 35 microgrammes per 100 millilitres of breath
  • 107 milligrammes per 100 millilitres of urine

In Scotland, the legal amount you can drink before driving is:

  • 50 milligrams of alcohol in every 100 millilitres of blood.
  • The breath alcohol equivalent is 22 micrograms of alcohol per 100 millilitres of breath.



Although many people think they are driving safely, alcohol impairs their judgement, reaction times and sense of reality.

It affects driving ability by causing: 

  • delayed reaction times
  • blurred vision
  • drowsiness
  • inability to think, reason or plan ahead
  • reduced concentration 
  • reduced ability to interpret road signs and speed limits
  • an inability to judge your position on the road, making it easy to cross the centre line etc
  • impaired assessment of risk.

The only safe limit is no alcohol

How the body processes alcohol differs from person to person, and this depends on a number of factors:

  • amount and type – how much alcohol has been taken how quickly
  • age – younger people have lower alcohol tolerance coupled with a lack of driving experience
  • weight/size – the smaller you are, the lower your blood volume is likely to be and alcohol may affect you more
  • gender – women are typically smaller and have proportionately more body fat and less body water than men so drinking the same amount of alcohol is likely to result in a higher blood alcohol concentration
  • water intake – dehydration leads to a higher concentration of alcohol in the blood
  • food intake – alcohol is absorbed more slowly if there is food in the body