UK drink-drive limit: England, Wales & NI vs Scotland, explained
The UK doesn't have one drink-drive limit. It has two sets of limits, each expressed three different ways, and a lot of advice pages blur the units together or quote only one jurisdiction. Highway Code Rule 95 covers the whole UK, but the actual numbers it enforces are lower in Scotland than in England, Wales and Northern Ireland — and the three measures (breath, blood, urine) aren't just the same number written differently. Here are the real figures, where they come from, and what happens if you're caught over them.
One rule, two sets of numbers
Rule 95 of the Highway Code says the same thing everywhere in the UK: don't drink and drive, because alcohol affects your judgement, coordination and reaction time long before you feel drunk. What differs by nation is the legal limit that rule is built on. England, Wales and Northern Ireland share one limit; Scotland adopted a lower one on 5 December 2014 and has kept it since. Each nation's limit is set three ways, because police can test breath, blood or urine depending on the circumstances:
| Measure | England, Wales & Northern Ireland | Scotland |
|---|---|---|
| Breath (micrograms per 100ml) | 35 | 22 |
| Blood (milligrams per 100ml) | 80 | 50 |
| Urine (milligrams per 100ml) | 107 | 67 |
Notice the units aren't the same across rows: breath is measured in micrograms, blood and urine in milligrams — a thousand times larger per unit. That's why "30 micrograms" and "50 milligrams" can both describe a result nowhere near each other's limit, and why quoting a breath figure against a blood limit (a mistake that turns up surprisingly often in casual summaries of this rule) produces a meaningless comparison. Always match the measure to the test that was actually used.
Worked example: how much stricter is Scotland, really?
Comparing the breath limits directly: 22 ÷ 35 = 0.63, so Scotland's limit is roughly 63% of the England/Wales/NI figure — a reduction of about a third, not a token adjustment. The blood and urine columns scale by almost exactly the same ratio (50/80 = 0.625; 67/107 = 0.626), which confirms the three measures aren't independently set: each nation picked one underlying strictness level and expressed it three ways for different test methods.
A separate, informal ratio worth knowing: dividing the blood limit by the breath limit in the same nation (80mg ÷ 0.035mg, converting breath to the same units) gives approximately 2,286:1, commonly rounded to about 2,300:1. That's not an official conversion factor published anywhere — it's just what falls out of the two legal numbers used side by side — but it explains why breath results look so much smaller than blood results for what is, legally, the identical limit.
Why there's no "safe number of drinks"
GOV.UK's own guidance is explicit that it's "impossible to say" how many drinks the limit equals, because the same drink affects different people differently. The factors it names: body weight, age, sex, metabolism, the type and amount of alcohol, how recently you've eaten, and even your stress level at the time. Two people who had an identical evening could legally be on opposite sides of the line the next morning. That uncertainty is also why a reading taken the morning after drinking can still be over the limit — alcohol clears the body at a roughly steady rate regardless of how long ago you stopped drinking, so "I slept for six hours" doesn't guarantee you're back under the limit by itself.
What happens if you're caught over the limit
The penalties, like the limits, are set out by offence rather than by how many drinks were involved:
| Offence | Prison | Fine | Driving ban |
|---|---|---|---|
| Driving or attempting to drive while over the limit or unfit through drink | Up to 6 months | Unlimited | At least 1 year (3 years if convicted twice in 10 years) |
| In charge of a vehicle while over the limit (not driving) | Up to 3 months | Up to £2,500 | Possible, not automatic |
| Refusing to provide a specimen of breath, blood or urine | Up to 6 months | Unlimited | At least 1 year (3 years if convicted twice in 10 years) |
| Causing death by careless driving while under the influence | Life imprisonment | Unlimited | At least 5 years, plus an extended retest before the licence returns |
Refusing a test carries the same maximum penalty as failing one — it isn't a way to avoid the consequences, which is the point of listing it alongside "driving while over the limit" rather than treating it as a lesser offence. Anyone banned for 12 months or more may be offered a place on a drink-drive rehabilitation scheme (DDRS) course by the court; completing it can shorten the ban, but the court decides case by case whether to offer it at all, and it isn't an automatic right.
Quick reference
| Question | Answer |
|---|---|
| Is the limit the same across the whole UK? | No — Scotland's is lower (22/50/67 vs 35/80/107, breath/blood/urine) |
| When did Scotland's limit change? | 5 December 2014 |
| Can I estimate my own result from "units" drunk? | No reliable way — GOV.UK says it varies too much by person |
| Does refusing a breath test avoid a penalty? | No — refusal carries the same maximum penalty as failing |
| Can a ban be shortened? | Possibly, via a DDRS course, for bans of 12+ months, at the court's discretion |
This is educational material, not legal advice — if you need to know exactly where you stand, check GOV.UK's current guidance or consult a solicitor rather than relying on any rule of thumb, including the ratios above. For more scenarios like the Scotland/England comparison tested here, try the hazard awareness practice questions.
Source: UK Highway Code, Rule 95 (gov.uk/guidance/the-highway-code/alcohol-and-drugs-95-to-96); gov.uk/drink-drive-limit; gov.uk/drink-driving-penalties.