Drink Drive Limit Calculator UK
Enter your gender, weight, number of drinks and time of first drink to estimate your blood alcohol content (BAC) and find out when you are likely to be under the legal limit. This calculator gives an estimate only, the only safe approach is not to drink at all if you are driving.
UK Drink Drive Limits Explained
The legal drink drive limit in the UK differs between Scotland and the rest of the country.
| Region | Breath (µg/100ml) | Blood (mg/100ml) | Urine (mg/100ml) |
|---|---|---|---|
| England, Wales & Northern Ireland | 35 | 80 | 107 |
| Scotland | 22 | 50 | 67 |
| The Road Traffic Act 1988 sets the drink drive limits for England, Wales and Northern Ireland, where the limit has remained unchanged since 1967. In Scotland the drink driving alcohol limit has been stricter than the rest of the UK since 2014. |
Important 2026 update: As part of the Road Safety Strategy launched in January 2026, the government is consulting on reducing the drink drive limit in England and Wales to 22 micrograms in breath, the level already used in Scotland. No law has changed yet, but the consultation closed on 31 March 2026 and a decision is expected. If you drive in Scotland, the lower limit already applies to you.
How BAC Is Calculated
Your blood alcohol content is affected by five key factors:
Body weight: alcohol distributes through body water, so a heavier person reaches a lower BAC from the same drinks than a lighter person.
Sex: women typically reach a higher BAC than men of the same weight because of differences in body water percentage and alcohol metabolism rates.
Number of drinks and strength: the total units consumed is the biggest single driver of your BAC reading.
Food: drinking on an empty stomach means alcohol enters your bloodstream significantly faster. A solid meal before or during drinking slows absorption and reduces peak BAC.
Time: your body eliminates alcohol at roughly one unit per hour on average, though this varies between individuals. Time is the only thing that genuinely reduces BAC.
Nothing else changes the rate at which alcohol leaves your system. A shower, a cup of coffee or other ways of "sobering up" may make you feel better but will not remove alcohol from your system.
How Alcohol Affects Your Driving
Even small amounts of alcohol affect your ability to drive safely before your BAC reaches the legal limit. Drinking affects your reaction times, your vision and your ability to concentrate, which means you cannot control the car as well. Many of the functions that we depend on to drive safely are affected when we drink alcohol, and you are more likely to engage in risk-taking behaviour after drinking.
This is why the police advice and the guidance from Drinkaware and the NHS, is consistent: if you are driving, do not drink at all. Even being well under the legal limit does not mean your driving is unaffected.
The Morning After Risk
One of the most underestimated dangers is driving the morning after a heavy evening. Alcohol stays in your system longer than you think. A typical bottle of wine at 13% ABV and 750ml contains about 10 units. Finish that at midnight and you could still be impaired at 10am.
If you have been out drinking, you may still be affected by alcohol the next day and could lose your licence if you drive and are still over the legal limit.
A rough guide: allow at least one hour per unit consumed before considering driving, plus an additional safety buffer. Use the morning-after section of our calculator above to estimate how long the alcohol you drank last night is likely to remain in your system.
Drink Drive Penalties UK 2026
Being caught over the legal limit carries serious consequences, even for a first offence.
Driving or attempting to drive over the limit:
| Severity | Penalties |
|---|---|
| Standard offence | Minimum 12-month driving ban, unlimited fine, up to 6 months imprisonment, criminal record |
| Causing death by drink driving | Up to 14 years imprisonment, minimum 2-year ban, extended retest required |
| Being "in charge" of a vehicle while over the limit is a separate and widely misunderstood offence. Being in charge of a vehicle while over the limit is a separate offence that catches people who are sleeping in a parked car, sitting in the driver's seat waiting, or otherwise in a position where they could drive. You can argue that there was no likelihood you would have driven, but that's a defence you would need to prove. The penalties include up to 3 months imprisonment and 10 penalty points. |
Refusing a breath test carries the same penalty as being found over the limit and automatically classifies you as a High Risk Offender with the DVLA, which means an additional medical hurdle before you can get your licence back.
High Risk Offender (HRO) Classification
Certain drink driving convictions trigger a separate classification with the DVLA. You will be flagged as a High Risk Offender if your alcohol reading was at least 87.5 micrograms in breath or 200 milligrams in blood, roughly two and a half times the legal limit or if you were convicted of two drink driving offences within 10 years, or if you refused to provide a specimen for analysis.
High Risk Offenders cannot simply wait out their ban and reapply. You must pass a DVLA medical examination that includes blood tests measuring biomarkers of alcohol consumption, and you pay for this yourself.
Is the UK Limit About to Change?
Estimates suggest that lowering the drink drive limit could reduce fatalities by between 25 and 100 annually. The government consultation, which ran until 31 March 2026, specifically explored bringing England and Wales into line with Scotland at 22 micrograms in breath and 50 milligrams in blood. A government decision on whether to proceed is expected later in 2026. No change is in force yet, the current limits of 35 micrograms in breath and 80 milligrams in blood remain the law in England, Wales and Northern Ireland.
Related Calculators
- Speeding Fine Calculator UK
- Road Tax Calculator UK
- Mileage Calculator UK
References
- GOV.UK. Drink Driving Penalties. gov.uk
- GOV.UK. Proposed Changes to Penalties for Motoring Offences, Consultation 2026. gov.uk, February 2026
- Drinkaware. Drink Driving and the Legal Alcohol Limit. drinkaware.co.uk
- Metropolitan Police. Alcohol and Drug Driving. met.police.uk
- LegalClarity. UK Drink Drive Limits: England, Scotland and Penalties. legalclarity.org, May 2026
- Bartlett Auto. Drink Driving Limits in the UK, What's Being Proposed. bartlett-auto.com, January 2026
- Road Traffic Act 1988. legislation.gov.uk
- SoftwareApplication