What Is the UK Limit for Drinking and Driving in Units?

Understanding the UK Drink Driving Limit in Alcohol Units

Driving under the influence of alcohol is a serious offence in the UK.

Understanding the legal limit is essential for staying safe and legal on the roads. 

While the law sets alcohol limits in terms of blood, breath, and urine alcohol levels, many people wonder what that translates to in more relatable terms, such as alcohol units.

 

What Are Alcohol Units?

In the UK, one alcohol unit is defined as 10 millilitres (or 8 grams) of pure alcohol. The number of units in a drink depends on both the volume and the alcohol by volume (ABV) percentage.

For example:

  • A standard 175ml glass of wine (13% ABV) = approx. 2.3 units
  • A pint of 5% beer = approx. 2.8 units
  • A single 25ml shot of 40% spirit = 1 unit

 

The Legal Limit in the UK

The legal alcohol limit for drivers in England, Wales, and Northern Ireland is:

  • 35 micrograms of alcohol per 100 millilitres of breath
  • 80 milligrams of alcohol per 100 millilitres of blood
  • 107 milligrams of alcohol per 100 millilitres of urine

In Scotland, the limits are stricter:

  • 22 micrograms per 100ml of breath
  • 50 milligrams per 100ml of blood
  • 67 milligrams per 100ml of urine

 

So, How Many Units Can I Drink and Stay Under the Limit?

Here’s where it gets tricky, there’s no universal answer. The number of units a person can drink and remain under the legal limit depends on a wide range of factors, including:

  • Body weight and metabolism
  • Gender
  • Age
  • Whether you’ve eaten
  • The type and strength of alcohol
  • Time elapsed since drinking

 

As a very rough guideline, the NHS has historically suggested that:

  • Men may stay under the limit with up to 2–3 units
  • Women may stay under with up to 1–2 units

But these are not guarantees. Even a small amount of alcohol can affect your reaction times, judgment, and ability to drive safely.

Remember, everyone reacts to alcohol differently!

 

The Safest Option: Don't Drink and Drive

Because everyone processes alcohol differently, the only truly safe amount to drink before driving is none at all. Even if you feel fine, your BAC (blood alcohol concentration) might be over the limit. Police can test you at the roadside with a breathalyser, and penalties for drink driving includes fines, driving bans, and criminal records.

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