A simples guide

A guide to drink driving limits

We all know we shouldn’t drink and drive. It reduces your reactions and driving ability, can land you with a lengthy ban, fine and even a prison sentence as a result. Which will obviously have serious consequences for you when it comes to insuring a car. But what exactly is drink driving? What’s the law and how do you interpret it in the real world?


When it comes to alcohol limits, the safest answer is not to drink anything at all. That way you just avoid any risks at all as alcohol effects people differently. But it’s important to know how much is too much.


How much can I legally drink when I’m driving?

Well first let’s look at the statistics. In 2012, 1,200 people were seriously injured in accidents that involved a drink driver and 280 were killed.

That is simply way too many, but it’s important to note that drink driving accidents have come right down over the last 35 years and the number of lives lost has fallen 75% since 1979.

 With regards to the legal limits. In England, Wales and Norther Ireland, the legal drink drive limit is:

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

In other European countries it is often less, around 50 milligrams per 100 millilitres of blood.

So the rule is not as simple as you can drink two bottles of beer, or one glass of wine for example and will affect everyone differently. 

social drinking

How quickly does alcohol break down?

We have all thought at some point, if I drink at lunchtime and will I be safe to drive later that evening? Effectively the body takes one hour to break down one unit of alcohol, as a rough guide. Of course you should always play it safe as it can vary wildly depending on your weight, gender, your age and your metabolic rate.

Other factors come into the equation too, including how much you have eaten, the type of alcohol, how much water you have drunk and more. It is not an exact science, so don’t try and cut it fine, be responsible and avoid the risk completely if you’re not sure. 

How much is one unit?

It’s all well and good talking about milligrams of alcohol in your blood, but what does that look like in your glass? How much is one unit?

Well one unit is 8g, or 10ml if you prefer, of pure alcohol. There are approximately:

  • 2.1 units in a 175ml standard glass of wine.
  • 3 units in a large glass of wine.
  • 2 units in a pint of normal lager, cider or beer.
  • 3 units in a pint of high strength lager and cider.
  • 1 unit in a measure of spirits.

So your body may take 3 hours, approximately, to break down a pint of high strength lager. But again, it can vary from person to person.

If you have a number of drinks during the course of the evening then you can still be over the legal drink drive limit the next day, so you need to be mindful if you know you have to drive in the morning and plan an alternative to driving.

What is the legal drink drive limit in Scotland?

In December 2014, the law was changed and the legal limit was reduced to:

  • 50 milligrams of alcohol in every 100mls of blood.
  • 22 micrograms of alcohol per 100mls of breath.

What are the penalties for drinking and driving?

The most serious offence is causing a fatal accident by careless driving while under the influence of alcohol or drugs. As the level of alcohol in your system increases, the likely penalty goes up too.

The maximum penalty is an unlimited fine and potentially 14 years in prison, with a minimum one-year term. You will also be disqualified for at least two years and a number of penalty points.

If you are caught driving, or attempting to control a vehicle, while under the influence of alcohol, you are likely to receive a ban of between one and three years, a large fine and potentially a 6-month prison sentence. The courts can also endorse your licence with penalty points that remain on your licence for up to 10 years.

On occasion, a Judge may grant a 25% reduction in the disqualification if you agree to a drink driving course. If you fail to provide a blood sample, this can be treated just as severely as a failed test, so you can expect a fine of up to £1,000 as well as a 36-month driving ban.


driving licence

How will a driving conviction or ban my insurance premium?

Obviously insurers will want to know if you have any driving convictions. Failure to mention any convictions you have will invalidate your policy and void your cover if you need to make a claim.

Having a conviction is also likely to make your premiums more expensive. However, you can use our car insurance comparison service to find the right deal for you.

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