SafeBAC CalculatorInformational BAC Tool

BAC Calculator UK – Blood Alcohol Limit and Drink-Driving Risks

Understand your estimated BAC and how it relates to drink-driving limits in the UK—but never use any calculator to decide if you can drive.

Estimate your BAC

Enter your details and drinks to see an approximate blood alcohol concentration. Results are only estimates and must not be used to decide if you can drive.

Use an approximate value if you are not sure. The estimate is sensitive to body weight.

This helps us compare your estimated BAC with commonly cited legal limits in your selected region.

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Count from the first sip of your first drink. The longer you have been drinking, the lower your BAC may be from metabolism.

Drinks you have consumed

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Never use BAC estimates to decide whether you can drive.

Estimated BAC and safety overview

These numbers are only rough estimates. Everyone processes alcohol differently.

Fill in your details and drinks, then select “Estimate BAC” to see estimated values and safety guidance.

Drink Driving Limits in the UK

The legal drink driving limits across the UK are measured in micrograms of alcohol per 100 millilitres of breath (µg/100ml), milligrams per 100 millilitres of blood (mg/100ml), or milligrams per 100 millilitres of urine (mg/100ml).

**England, Wales, and Northern Ireland:**
- **Blood:** 80mg/100ml (0.08% BAC)
- **Breath:** 35µg/100ml
- **Urine:** 107mg/100ml

**Scotland:**
- **Blood:** 50mg/100ml (0.05% BAC)
- **Breath:** 22µg/100ml
- **Urine:** 67mg/100ml

**Important:** Scotland's lower limit means that even a single drink could put some drivers over the limit. There is no foolproof way to drink and stay under the limit, as it depends on your weight, age, sex, metabolism, and even stress levels.

Safety & Penalties

Penalties for Drink Driving: You could face imprisonment, a driving ban, and an unlimited fine if found guilty. The actual penalty depends on the magistrates who hear your case and depends on your specific offence.

**The "Morning After" Risk:**
You can still be over the limit the morning after drinking. Sleep, coffee, and cold showers do not speed up alcohol elimination. Time is the only way to get alcohol out of your system.

**Safest Advice:**
The safest advice is to avoid alcohol completely if you are driving. If you plan to drink, arrange a designated driver, use public transport, or book a taxi.

UK Drink Driving FAQ

There is no safe number of units. The way alcohol affects you depends on your weight, age, sex, and metabolism. You could be over the limit after just one drink.
Yes. Scotland has a stricter limit (50mg of alcohol per 100ml of blood) compared to England, Wales, and Northern Ireland (80mg/100ml).
It takes time for alcohol to leave your system. If you've had a lot to drink, you may still be over the limit the next morning. If in doubt, do not drive.

Switch country

View BAC estimates and drink-driving information for other regions: