Drink Drive Limit Calculator NHS
This independent UK drink-drive checker shows the current legal breath, blood and urine alcohol limits for the part of the UK you select. It deliberately does not estimate whether a number of drinks leaves you safe or legal to drive, because GOV.UK states that it is impossible to say exactly how many drinks equal the legal limit.
UK drink-drive limit checker
Safety: Do not use this checker to decide how much alcohol you can drink before driving. Any alcohol can impair driving, and the safest approach when planning to drive is not to drink.
Current UK legal limits
| Measure | England, Wales & Northern Ireland | Scotland |
|---|---|---|
| Breath | 35 micrograms / 100 ml | 22 micrograms / 100 ml |
| Blood | 80 mg / 100 ml | 50 mg / 100 ml |
| Urine | 107 mg / 100 ml | 67 mg / 100 ml |
Why there is no drinks-to-driving formula
The legal limits measure alcohol in breath, blood or urine, not the number of drinks consumed. Alcohol levels vary with factors including body weight, age, sex, metabolism, the type and amount of alcohol, food and other individual circumstances. A unit calculator can tell you how much pure alcohol a drink contains, but it cannot reliably tell you whether you are below the driving limit.
Alcohol units are different from the driving limit
NHS guidance calculates alcohol units as ABV (%) × volume (ml) ÷ 1,000. This is useful for tracking drinking, but there is no reliable conversion from a number of units to a legal breath or blood reading for an individual.
Worked example
If you select Scotland, this checker displays the Scottish limits of 22 micrograms per 100 ml of breath, 50 mg per 100 ml of blood and 67 mg per 100 ml of urine. It does not tell you that a particular drink quantity is safe before driving.
Driving the next morning
Alcohol takes time to leave the body. The Highway Code warns that you may still be unfit to drive in the morning after drinking the previous evening. Do not rely on coffee, sleep, food, showers or an online calculator to prove that you are fit to drive.
Limitations
This checker only displays published legal thresholds. It cannot measure your alcohol concentration, predict a breathalyser result or determine whether you are fit to drive. Legal limits can also change, so official government guidance remains the source of truth.
Authoritative Sources
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FAQs
How many drinks can I have and still drive legally?
There is no reliable number. GOV.UK says it is impossible to say exactly how many drinks equal the legal limit because alcohol affects people differently.
Is the drink-drive limit lower in Scotland?
Yes. Scotland currently has lower breath, blood and urine limits than England, Wales and Northern Ireland.
Can alcohol units tell me if I am safe to drive?
No. Units describe the amount of pure alcohol in a drink; they do not reliably predict an individual’s breath or blood alcohol concentration.
Can I use this calculator the morning after drinking?
You can check the legal thresholds, but this tool cannot tell you whether alcohol has left your body or whether you are fit to drive.
Safety disclaimer: Never use an online calculator to decide whether to drive after drinking. If you have been drinking, arrange another form of transport.