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Drink Driving in the UK

Alcohol Units & BAC (blood alcohol content)

None for the Road

Even the smallest amounts of alcohol can impair a drivers judgment. The rate at which alcohol increases a persons BAC (blood alcohol concentration) can vary according to numerous factors which include the following:-

  • An individuals metabolism rate
  • A persons sex
  • Various health issues
  • Amount of food in the stomach and small intestine
  • A persons weight
  • How long they have been drinking

On average, after the first 30 mins to 1 hour for the alcohol to be fully absorbed, your body will break down one unit of alcohol per hour. Each unit will increase your BAC by 15mg (up to 30mg for women).

Only 10 minutes after having a drink, 50% of the alcohol will be in your bloodstream.

What is a unit?

A UK unit is 10ml or 8 grams of pure alcohol (also called ethanol).

The number of units in an alcoholic drink depends on how strong the drink is and how much there is. Some manufacturers are starting to label their products with unit values so that you can work out how much you are drinking more easily.

To find out how many units are in an alcoholic drink:

Multiply the volume in milliliters (one pint is 568ml; a standard glass of wine 175ml) by %ABV then divide the result by 1000.

For example, if you order a pint of strong lager at 8% ABV:

1 pint (568ml) X 8 = 4,544

Divided by 1,000 = 4.544, or 4.5 units

WARNING: There is no safe way to calculate your BAC as it relies on so many factors. The only safe and fool proof way is to use a reliable breathalyser or even better still, do not drink and drive!!

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