Drink Drive Limit Calculator UK
Instantly estimate your Blood Alcohol Concentration (BAC) and see how long until you are safe to drive. Check your status against both England and Scotland legal limits.
Blood Alcohol Concentration (BAC)
Estimate your BAC and time until safe to drive
Gender affects the Widmark factor (r) due to differences in body water composition.
Enter your weight in kilograms (kg). 1 stone = 6.35 kg.
1 UK unit = 8g of pure alcohol. Check the reference table below for common drinks.
How many hours have passed since you finished your last drink?
Your Estimated BAC
Drink drive limit status
Enter your details and click Calculate to see your estimated Blood Alcohol Concentration and time until safe to drive.
Common Drinks & Units of Alcohol
Use this table to estimate how many units are in your drink. 1 UK unit equals 10ml (or 8g) of pure alcohol.
| Drink Type | Serving Size | ABV | Units |
|---|---|---|---|
| Pint of standard lager | 568ml | 4% | 2.3 |
| Pint of strong lager/beer | 568ml | 8% | 4.5 |
| Small glass of wine | 175ml | 12% | 2.1 |
| Large glass of wine | 250ml | 12% | 3.0 |
| Single shot of spirits | 25ml | 40% | 1.0 |
| Bottle of alcopop | 275ml | 5% | 1.4 |
| Pint of cider | 568ml | 5% | 2.8 |
| Large spirit & mixer | 50ml + mixer | 40% | 2.0 |
Drink Drive Limit FAQ
Everything you need to know about the UK drink drive limit, BAC, and staying safe on the roads.
In England, Wales, and Northern Ireland, the legal blood alcohol limit is 80 milligrammes of alcohol per 100 millilitres of blood (35 microgrammes per 100 millilitres of breath). In Scotland, the limit is lower at 50 milligrammes per 100 millilitres of blood (22 microgrammes per 100 millilitres of breath).
There is no foolproof way to know exactly how many units you can drink and still be under the limit, as it depends on your weight, gender, age, and metabolism. However, as a rough guide, most people will exceed the limit after 2-3 pints of strong beer or 2 large glasses of wine. The safest advice is to not drink any alcohol if you are planning to drive.
The human body breaks down alcohol at a relatively constant rate of about 1 unit (8g) per hour, or roughly 15mg/100ml per hour. This means if you drink 6 units at 11 PM and stop at midnight, it will take approximately 6-7 hours for the alcohol to completely leave your system, making it unsafe to drive until around 6 AM or 7 AM.
Many people are caught drink driving the morning after a night out. Alcohol can remain in your blood for hours after you stop drinking. If you had a heavy night of drinking, you could easily be over the legal limit the next morning. Always calculate how long it will take for the alcohol to leave your system before getting behind the wheel.
The penalties for drink driving are severe. You can face an unlimited fine, a driving ban for at least 1 year (3 years if convicted twice within 10 years), and up to 6 months in prison. If you cause death by careless driving while under the influence, you can face up to 14 years in prison, an unlimited fine, and an extended driving test before your licence is returned.
Scotland has a stricter drink drive limit than the rest of the UK. The limit is 50 milligrammes of alcohol per 100 millilitres of blood (22 microgrammes per 100 millilitres of breath). This was introduced in December 2014 to bring Scotland in line with most other European countries.
No. While eating food before drinking can slow the absorption of alcohol into your bloodstream, it does not change the total amount of alcohol you have consumed. Drinking water or coffee, taking a cold shower, or exercising will not speed up the elimination of alcohol from your blood. Only time can lower your BAC.
BAC is typically estimated using the Widmark formula, which factors in the total amount of alcohol consumed (in grams), your body weight, and your gender (as men and women metabolise alcohol differently due to body water composition). The formula then subtracts the elimination rate (about 15mg/100ml per hour) based on the time passed since your last drink.