Drink-Driving Limits in Ireland: 50 mg, 20 mg and Specified Drivers

Ireland has two drink-driving limits, not one. Most drivers are on 50 mg of alcohol per 100 ml of blood. Learners, newly qualified drivers and anyone without a licence for what they are driving are on 20 mg — and so is anyone, however experienced, while they drive a truck, a bus, a work vehicle, a car with a heavy trailer or a taxi at work.

That last part is the one people get wrong, because the lower limit follows the vehicle as well as the driver. Here is what the Road Traffic Act 2010 says, what it looks like in pints, and why the border with Northern Ireland changes the number.

The Two Limits at a Glance

Road Traffic Act 2010, sections 3 and 4, as revised to 2026.

Three details in the wording matter. The offence is to exceed the limit, so a reading of exactly 50 mg is not over it. The test is your level within 3 hours after you drove, not only at the roadside. And being in charge of a vehicle with intent to drive (section 5) uses the same limits as driving it.

On summary conviction the maximum penalty is a fine of up to €5,000, up to 6 months in prison, or both (section 4(5)). The Act also provides fixed penalties for some lower readings; for the current amounts and their consequences for your licence, check Citizens Information or the Road Safety Authority rather than a summary.

Who Is a “Specified Person”?

Section 3 of the Act lists who is held to 20 mg. The list splits into two groups: people who are on the lower limit because of their licence, and people who are on it because of the vehicle they are driving at that moment.

Because of your licence

• Learner permit holders, for the category of vehicle they are driving. A full car-licence holder who also has a truck learner permit is not caught by this rule while driving their car.
• Novice drivers: anyone within 2 years of the date their first driving licence was issued. The period runs from the first licence, so adding a category later does not start it again.
• Anyone without a licence for the category of vehicle they are driving — including a car driver towing a BE combination without the BE entitlement.

Because of the vehicle

• Trucks and buses: categories C, C1, D and D1, and their trailer combinations CE, C1E, DE and D1E.
• A car towing a heavy trailer: category BE. The Act still says “EB”; since 31 July 2023 the Road Traffic Acts are read with the current name, BE.
• Work vehicles: category W.
• Taxis and other small public service vehicles (SPSVs) while used in the course of business — and anyone who acts as an SPSV driver without the licence, carrying passengers for reward.

It Follows the Vehicle, Not the Person

The vehicle rules apply while you are driving, trying to drive or in charge of that kind of vehicle. A truck driver who drives home in their own car is on the general 50 mg limit for that journey, and so is a taxi driver off duty in a private car. The lower limit returns the moment they climb back into the truck or start working in the taxi.

There is a catch. If you hold a truck, bus, BE or W licence, or an SPSV driver licence, the law presumes you were driving that kind of vehicle “until the contrary is shown” (section 3(2)). In practice it is for the driver to show what they were actually driving.

Towing is where most car drivers meet the rule. A car with a trailer of up to 750 kg, or any car-and-trailer combination up to 3,500 kg in total, is still category B, so an experienced driver towing it is on 50 mg. Heavier outfits generally need the BE category, and a BE combination is on the 20 mg list. Where the line falls for your own car and trailer is a question for the NDLS or the RSA.

Learners, Novices and Licences From Abroad

The novice period is 2 years from the date your first driving licence was issued. If you learned to drive in another country, the position is less clear. For N-plates, the licensing authority counts time held on an EU/EEA or exchange-country licence, but no official source says how that maps onto the drink-driving definition of a “first driving licence”.

Alcophone takes the cautious reading. It asks whether you are a learner, or got your first full licence — in any country — less than 2 years ago, and if so it checks your estimate against 20 mg.

Learner permits themselves are changing: from 1 November 2026, new rules stop learners renewing their permits again and again without taking a test. That affects how long people stay learners, not the limits.

What 20 mg and 50 mg Look Like in Pints

In Ireland a standard drink is 10 grams of pure alcohol, and the HSE counts half a pint of 4.5% beer, stout or cider as one. A full 568 ml pint at 4.5% holds 20.2 g — 2.0 standard drinks. Here is the highest estimated BAC, in mg per 100 ml, after one to three pints drunk one an hour:

Illustrative estimates from Alcophone’s model (Jackson 2002 body-fat + Norberg distribution, sex- and age-based elimination at the empty-stomach rate), on an empty stomach. Profiles: 100 kg man, 183 cm, 40; 82 kg man, 178 cm, 30; 64 kg woman, 165 cm, 30; 54 kg woman, 160 cm, 25.

One pint takes every profile in the table over 20 mg — the limit a learner, a novice or a bus driver at work is held to. Two pints, an hour apart, take every profile over the general 50 mg limit as well.

These are estimates from a model, not a measurement. Food slows absorption, people differ, and a breath or blood test measures what is actually in your body. The only amount that keeps you under 20 mg for certain is none.

The Morning After: When Does 20 mg Arrive?

For a bus, truck or taxi driver, the risky drive is often not the one home from the pub but the first shift the next morning. Here are the same profiles after four pints, one an hour from 20:00 to 23:00, and the time each estimate falls to 50 mg, to 20 mg and to zero:

Illustrative estimates from Alcophone’s model (Jackson 2002 body-fat + Norberg distribution, sex- and age-based elimination at the empty-stomach rate), on an empty stomach. Profiles: 100 kg man, 183 cm, 40; 82 kg man, 178 cm, 30; 64 kg woman, 165 cm, 30; 54 kg woman, 160 cm, 25. Times are rounded up to the next 10 minutes.

Even for the 100 kg man the estimate does not fall to 20 mg until about 07:00, so nobody in the table is under the professional limit for a shift that starts at 06:00. At 08:00 both women are still over the general 50 mg limit. Sleep, coffee and a shower do not move these times; only time does.

Northern Ireland Is Different

Northern Ireland is part of the UK, and its limit is 80 mg per 100 ml of blood — the same as England and Wales, with no separate limit for learners or new drivers. A law to lower it has been passed but, as of September 2026, has not been brought into force. So the same reading can be under the limit on one side of the border and an offence on the other: an experienced car driver at 60 mg is over the limit in Dundalk and under it in Newry. See the UK limits for the details, and limits by country for the rest of the world.

What Alcophone Does in Ireland

Pick Ireland and the app uses the Irish standard drink of 10 g, pint-sized beer and cider presets, and the 50 mg limit. Settings › Driving has two switches for the 20 mg cases: one for learners and novice drivers, and one for professional, towing and heavy-vehicle driving, which you switch on for those trips and off again when you are back in your own car. The full limit table is on BAC limits in Ireland.

You must be 18 to buy alcohol in Ireland. In an emergency, call 112 or 999 — both work and are answered the same way.

The Practical Version

• 50 mg for most drivers; 20 mg for learners, novices in their first 2 years and unlicensed drivers.
• 20 mg for anyone while driving a truck, a bus, a BE combination, a work vehicle or a taxi at work — and 50 mg again in their own car.
• A car with a light trailer is category B: 50 mg for an experienced driver.
• One pint can be enough to pass 20 mg, and four pints at night can still be over it the next morning.
• Northern Ireland is on 80 mg; the Irish limit is lower.
• No limit and no app tells you that you are fine to drive. Never drive after drinking.

Frequently Asked Questions

What is the drink-driving limit in Ireland?

50 mg of alcohol per 100 ml of blood (22 µg per 100 ml of breath) for most drivers, and 20 mg (9 µg of breath) for “specified persons”: learner permit holders, drivers within 2 years of their first licence, unlicensed drivers, and anyone driving a truck, bus, BE combination, work vehicle or a taxi at work. The offence is to exceed the limit, judged on your level within 3 hours after driving.

Is a truck or bus driver on 20 mg in their own car?

No. The professional part of the 20 mg rule applies while driving that kind of vehicle. A truck driver in their own car, or a taxi driver off duty in a private car, is on the general 50 mg limit — but the law presumes a holder of a truck, bus, BE, W or taxi licence was driving that kind of vehicle until they show otherwise.

Does towing a trailer put me on the 20 mg limit?

Not with a light trailer. A car with a trailer of up to 750 kg, or a car and trailer that together weigh up to 3,500 kg, is category B, so an experienced driver is on 50 mg. Driving a BE combination puts you on 20 mg, and so does towing one without a BE licence.

Is the drink-driving limit different in Northern Ireland?

Yes. Northern Ireland is part of the UK and its limit is 80 mg per 100 ml of blood, with no separate limit for learners or new drivers. Crossing the border changes the law, not your blood alcohol: plan on the Irish limit, or better, on none at all.

Full limit tables by country: USA (50 states + DC) · Canada · Australia · United Kingdom · India · Ireland