Drink Driving Limit UK: England, Wales, Scotland, NI

The UK's drink drive limit is not one figure for the whole country. England, Wales and Northern Ireland share a blood alcohol limit of 80mg per 100ml, but Scotland has applied a stricter 50mg limit since December 2014, with its own breath and urine limits too.

The Drink Drive Limit by Nation

The limit is measured in three ways: the amount of alcohol in your blood, your breath, or your urine. Whichever measurement the police use, going over any one of these figures for your nation is the offence.

Scotland's lower limit has applied since 5 December 2014, when the Scottish Government used its devolved powers to set a stricter threshold than the rest of the UK. Northern Ireland is also a devolved nation, but its drink drive limit has stayed aligned with England and Wales rather than following Scotland's example, so it is worth checking which limit applies before you drive across the Irish border or between Great Britain and Northern Ireland.

Why You Can't Convert the Limit into "Units" or Drinks

There is no dependable rule of thumb, such as "two pints" or "a large glass of wine", that tells you whether you are under the limit. How much alcohol ends up in your blood, breath or urine after a given drink depends on your body weight, your sex, your metabolism, how much food you have eaten, how quickly you drank, and even the specific drink's strength. Two people who have had exactly the same drinks can produce very different readings, and the same person can vary from one occasion to the next.

Because of that variation, gov.uk and Police Scotland do not publish a "safe" number of units or drinks that guarantees you will stay under the limit. The only way to be certain you are not breaking the law is not to drink any alcohol at all before driving. If you have been drinking the night before, bear in mind that alcohol can still be in your system, and above the limit, the following morning.

Roadside Testing and Refusing a Test

Police can stop a vehicle and require the driver to take a preliminary breath test at the roadside if they suspect the driver has alcohol in their body, has committed a moving traffic offence, or has been involved in a road traffic accident. If that roadside test suggests you are over the limit, or you fail it, you can be arrested and taken to a police station for an evidential breath, blood or urine test, which is the sample used in any prosecution.

Refusing to provide a specimen without a reasonable excuse is itself an offence, separate from and in addition to drink driving, and is generally treated by the courts in a similar way to driving over the limit. There is no legal right to refuse a breath test because you would rather have a blood or urine test instead, or to insist on speaking to a solicitor before providing a roadside sample.

What Happens if You're Over the Limit

Driving, attempting to drive, or being in charge of a vehicle over the relevant limit is a criminal offence with serious consequences, including a lengthy driving ban, an unlimited fine and a possible prison sentence. The full penalties, how a second offence within ten years is treated more harshly, and how the drink drive rehabilitation course can reduce a ban are set out on the drink driving ban page.

A drink driving conviction also carries a DR10 endorsement on your licence, which stays on your driving record for 11 years and can significantly increase your insurance costs. For how endorsements and points work more generally, see the penalty points guide.

This article is for general information only and is not legal advice. If you are facing a drink driving investigation or charge, get advice from a solicitor as soon as possible, since the details of your case will affect the outcome. For more on UK motoring law, see the UK Driving Laws hub and the United Kingdom hub, or read about speeding fines and penalty points.