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Ireland

Blood Alcohol Concentration (BAC) Calculator 🇮🇪

Calculate your estimated Blood Alcohol Concentration (BAC) instantly. Track standard drinks, view sobriety charts, and check your status against the 50mg (0.05%) Irish legal limit.

50 mg/100 ml Legal limit

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Drink Driving in Ireland — 50 mg/100 ml

The 20 mg/100ml limit (0.02% BAC) applies to learner permit holders, newly qualified drivers (first 2 years) and professional drivers (HGV, bus, taxi, public service vehicles). Penalties under the Road Traffic Act start at automatic disqualification — even a single drink can put you over the limit.

ℹ️ Information

CONTEXT
🌎 Country
Show results in
ABOUT YOU
Sex
⚖️ Weight

lbs

⏱️ Start time of drinking (optional) Time of your first drink (not required)

🕒

⏳ Or: hours ago —
0h6h12h18h24h

🍹🍸🍺 Drinks

Drink {{ index+1 }}

{{ drinkSummary(drink) }}

%

≈ {{ servingHint(drink) }}

Maximum number of drinks reached.

The results will show up here...
📈 Results
Current BACPeak BAC {{ initialSobriety }}{{ unitSign }} Legal limit {{ countryLimit }}{{ unitSign }}
Safe Caution Impaired Intoxicated Dangerous
Above the legal limit – do not drive. Close to the legal limit – driving not recommended. Safe to drive, but stay cautious.
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Sober in: {{ sobrietyTime }}

Drink Driving in Ireland

Experienced drivers 50 mg/100ml
Learner & professional drivers 20 mg/100ml

Penalties for Drink Driving in Ireland

Offence type No offence Below the legal limit – driving is permitted.
Offence type Over the 0.0 limit Zero-tolerance country — driving with any detectable alcohol is prohibited.
Offence type Over the legal limit You are over the legal limit and committing a drink-driving offence. Exact penalties depend on your BAC and local law.
Offence type Fixed-charge drink-driving offence 50–99 mg/100 ml (fixed-charge band) Fixed-charge offence — fine and automatic disqualification, no court if accepted.
Typical penalties
  • Fixed-charge penalty €200 (50–80 mg) or €400 (80–100 mg)
  • Automatic 3-month disqualification (50–80 mg) or 6 months (80–100 mg)
  • No court appearance if accepted
Offence type Drink driving (court conviction) 100+ mg/100 ml (court conviction) Criminal offence — may result in a criminal record.
Typical penalties
  • Court fine up to €5,000 and/or 6 months imprisonment
  • 2-year disqualification (100–150 mg) or 3-year (150+ mg) on first offence
  • Vehicle seizure standard during proceedings
These are general penalties. Actual consequences may vary by local law and circumstances. Learn more →

Legal limit

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Based on Irish law ·

Elimination rate

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Assumed average

Standard Drinks

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Approx. consumed

Pure Alcohol

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Pure alcohol consumed

Pure Alcohol (g)

{{ alcoholGrams }} g
Total ethanol consumed

Calories

{{ calories }} kcal
From alcohol only — mixers add more

Time over limit

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Estimated duration above the legal driving limit
For your own safety, we recommend using a rate no higher than the average.
Current BACPeak BAC {{ initialSobriety }}{{ unitSign }} Legal limit {{ countryLimit }}{{ unitSign }}
Safe Caution Impaired Intoxicated Dangerous
Above the legal limit – do not drive. Close to the legal limit – driving not recommended. Safe to drive, but stay cautious.
{{ legalLimitTimeLabel }}
Sober in: {{ sobrietyTime }}

Drink Driving in Ireland

Experienced drivers 50 mg/100ml
Learner & professional drivers 20 mg/100ml

Penalties for Drink Driving in Ireland

Offence type No offence Below the legal limit – driving is permitted.
Offence type Over the 0.0 limit Zero-tolerance country — driving with any detectable alcohol is prohibited.
Offence type Over the legal limit You are over the legal limit and committing a drink-driving offence. Exact penalties depend on your BAC and local law.
Offence type Fixed-charge drink-driving offence 50–99 mg/100 ml (fixed-charge band) Fixed-charge offence — fine and automatic disqualification, no court if accepted.
Typical penalties
  • Fixed-charge penalty €200 (50–80 mg) or €400 (80–100 mg)
  • Automatic 3-month disqualification (50–80 mg) or 6 months (80–100 mg)
  • No court appearance if accepted
Offence type Drink driving (court conviction) 100+ mg/100 ml (court conviction) Criminal offence — may result in a criminal record.
Typical penalties
  • Court fine up to €5,000 and/or 6 months imprisonment
  • 2-year disqualification (100–150 mg) or 3-year (150+ mg) on first offence
  • Vehicle seizure standard during proceedings
These are general penalties. Actual consequences may vary by local law and circumstances. Learn more →
{{ afterLabel }} {{ $t('unit.' + units) }} Status
{{ result.time }} {{ result.drunkenness }}
  • Safe to drive, but stay cautious.
  • Close to the legal limit – driving not recommended.
  • Above the legal limit – do not drive.
Create a pop-up notification

Sobriety Over Time

Your estimated BAC as your body clears the alcohol

Sober in {{ sobrietyTime }}
  • {{ lookaheadBacDisplay }}{{ unitSign }} Above the legal limit – do not drive. Close to the legal limit – driving not recommended. Safe to drive, but stay cautious.
  • {{ $t('unit.' + units) }}
  • Legal limit ({{ countryLimit }}{{ unitSign }})
👮 Health impact and legal consequences
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Peak BAC: {{ peakBAC }}

💡 Tips: drink water, eat, and avoid driving until below the legal limit and ideally sober.

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Attention‼️ The results are only approximate, so make sure you are sober before driving.

About results
Current BAC

Your Current BAC is the estimated alcohol in your blood right now. Irish law is written in milligrams per 100 ml of blood, so 50 mg/100 ml matches 0.05% — the figure the Gardaí measure at a mandatory alcohol checkpoint.

Legal limit

The general limit is 50 mg/100 ml (0.05% BAC), but it drops to 20 mg/100 ml (0.02%) for learner permit holders, drivers in their first two years, and professional drivers (HGV, bus, taxi and public-service vehicles). Under the Road Traffic Act even a single drink can push a learner or professional over, and exceeding the limit brings an automatic disqualification.

Elimination rate

The liver burns off alcohol at a steady pace of about 15 mg/100 ml (0.015%) an hour, and nothing speeds it up. Tea, water, food or fresh air may make you feel sharper while your true reading falls just as slowly — which is why a late night can leave you over the limit the next morning.

Standard Drinks

An Irish standard drink holds 10 grams of alcohol — a half-pint of stout, a small glass of wine, or a pub measure of spirits. A pint is close to two standard drinks, so a couple of pints already carries most drivers toward the limit.

Pure Alcohol

The pure alcohol (in grams) your body has taken on so far — the basis for both your standard-drink count and your BAC.

Time vs. Sobriety Table

The table projects your BAC each hour, and when you enter the time of your first drink it aligns the estimates to the actual time of day, so you can see when you are likely to drop below 50 mg/100 ml (or 20 mg/100 ml). Status icons flag the hours that are safe to drive; leave the time blank to work in hours elapsed.

Sobriety Over Time Graph

A line chart of your BAC declining over the hours ahead, showing when it falls below the Irish drink-drive limit and below a genuinely safe level.

How Alcohol Affects You

A reference table matching BAC ranges to their typical effects on judgement, coordination and reaction time — impairment that starts well before the legal limit.

Legal limit reached in / Sober in / Peak BAC

Quick summary estimates:

  • Legal limit reached in: time until your BAC falls below the applicable limit (50 or 20 mg/100 ml).

  • Sober in: time until it returns to ~0.

  • Peak BAC: the highest level reached in the session.

Data used for calculations

Five factors that determine your result

Weight
Body weight determines how alcohol distributes in the body — more weight means a lower blood alcohol concentration.
Sex
Men and women metabolise alcohol at different rates because of differences in body water content.
Amount
The amount of pure alcohol consumed is the main factor that determines your BAC result.
Strength
A higher strength (%) means more ethanol in the same drink serving.
Time
The time of your first drink shows how BAC changes hour by hour and when you'll be sober again.

How much does Ireland drink?

Alcohol consumption per adult, per year

10.5L

litres of pure alcohol per adult (15+), per year

Per adult, that is roughly:

370 beers ≈ 7/week
583 glasses of wine ≈ 11/week
656 shots ≈ 13/week
10.5 L
0.7 L Ø 8.9 17.1 L

18% above the regional average

Ranks #22 of 51 in Europe Ranks #28 of 188 in the World Average in Europe: 8.9 L

How neighbours compare

#1 France 11.2L #12 Europe
#2 United Kingdom 10.9L #18 Europe
#3 Scotland 10.9L #18 Europe
#4 Ireland 10.5L #22 Europe
#5 Netherlands 8.7L #30 Europe
#6 Belgium 8.7L #30 Europe

How safe are the roads in Ireland?

Road traffic deaths per 100,000 people, per year

3.2 /100k

road traffic deaths per 100,000 people, 2024

~46% of road deaths linked to alcohol WHO estimate, 2019 · 33–60%
3 road deaths per week WHO estimate, 2024
2 alcohol-linked deaths per week WHO-derived estimate
3.2
0.0 Ø 6.7 17.2

52% fewer road deaths than the regional average

#10 safest of 53 in Europe #14 safest of 195 worldwide Average in Europe: 6.7 per 100k

How neighbours compare

#1 United Kingdom 2.4 #6 Europe
#2 Scotland 2.4 #6 Europe
#3 Ireland 3.2 #10 Europe
#4 Netherlands 3.2 #11 Europe
#5 Belgium 4.0 #16 Europe
#6 France 4.6 #19 Europe

Latest available year shown per country.

LIMITS NEARBY

BAC limits in neighbouring countries

Explore the legal blood alcohol concentration (BAC) limits for drivers in neighbouring countries.

UK

United Kingdom

80mg/100 ml
Relaxed
SCOT

Scotland

50mg/100 ml
Moderate
FR

France

50mg/100 ml
Moderate
NL

Netherlands

50mg/100 ml
Moderate
BE

Belgium

50mg/100 ml
Moderate

Drink Driving in Ireland

Drink-driving limits in Ireland (blood alcohol)

Experienced drivers
50mg/100ml
Moderate
Learner & professional drivers
20mg/100ml
Strict
The 20 mg/100ml limit (0.02% BAC) applies to learner permit holders, newly qualified drivers (first 2 years) and professional drivers (HGV, bus, taxi, public service vehicles). Penalties under the Road Traffic Act start at automatic disqualification — even a single drink can put you over the limit.

Penalties for Drink Driving in Ireland

Consequences of exceeding the legal drink-drive limit

50–99 mg/100 ml (fixed-charge band)
Fixed-charge drink-driving offence
  • Fixed-charge penalty €200 (50–80 mg) or €400 (80–100 mg)
  • Automatic 3-month disqualification (50–80 mg) or 6 months (80–100 mg)
  • No court appearance if accepted
100+ mg/100 ml (court conviction)
Drink driving (court conviction)
  • Court fine up to €5,000 and/or 6 months imprisonment
  • 2-year disqualification (100–150 mg) or 3-year (150+ mg) on first offence
  • Vehicle seizure standard during proceedings

Tips for Responsible Drinking

Practical tips for safer drinking

Pace yourself
Stick to the "one drink per hour" rule – your liver needs time to process alcohol.
Eat before and while drinking
A solid meal slows alcohol absorption – an empty stomach raises BAC faster.
Drink water
After each alcoholic drink, have a glass of water – it reduces dehydration and health risks.
Don't drive
Even small amounts of alcohol impair reaction time. If in doubt, call a taxi or stay overnight.

Source: Road Safety Authority (RSA) Ireland.

How we calculate your BAC

The exact formula, step by step

Your result is not a guess. It comes from the Widmark equation, the same formula forensic toxicologists use in court. Here it is, worked through with an example.

BAC = A ÷ (r × W) − (β × t)

where A = grams of pure alcohol, r = body-water factor (0.68 for men, 0.55 for women), W = weight in kg, β = elimination rate (~0.15 g/L per hour), and t = hours since your first drink.

  1. Pure alcohol (A). Three 500 ml beers at 5% ABV hold 3 × 500 × 0.05 × 0.789 ≈ 59 g of pure alcohol.
  2. Body water (r × W). For an 80 kg man: 0.68 × 80 = 54.4.
  3. Peak level. A ÷ (r × W) = 59 ÷ 54.4 ≈ 1.09 g/L — the same as 1.09‰ or about 0.11% BAC.
  4. Subtract elimination. After 2 hours: 1.09 − (0.15 × 2) = 0.79 g/L.

The calculator runs this same equation on your own weight, sex, drinks and timing — the numbers above are only a worked example. Method based on E. M. P. Widmark (1932); results are an estimate, not a legal measurement.

What people actually log

SmartBAC has run over 17,000 calculations in recent weeks. Of every drink people log, beer is the most common by far — about 6 in 10 — ahead of spirits and then wine.

Anonymous, aggregated first-party usage data from SmartBAC, July–August 2026.

FAQ

How long does alcohol stay in your system?

The time it takes your body to clear alcohol is often underestimated. Once absorbed, alcohol is broken down mainly in the liver at a relatively constant rate, and this cannot be significantly sped up by water, coffee or exercise. A single standard drink may take one to two hours to be metabolised, and several drinks consumed quickly can keep your BAC elevated for many hours, well into the next day.

People who drink heavily or regularly may also have liver damage, which slows down alcohol metabolism and increases the risk of long‑term health problems. Planning alcohol‑free days, spacing out your drinks and allowing plenty of time before driving are important parts of reducing both health risks and the risk of drink driving.

Can I sober up faster after drinking?

Many traditional “hangover cures” in Ireland and elsewhere, such as strong tea or coffee, a fry‑up, a cold shower or a brisk walk, may make you feel temporarily more alert but do not reduce your BAC. Your liver continues to metabolise alcohol at its own pace, regardless of what you eat or drink afterwards. The only reliable way to get alcohol out of your system is to give it time and to rest.

If you need to travel, plan to use public transport or a taxi rather than relying on these myths. Feeling sharper does not mean your reflexes and judgment are back to normal, and the legal drink drive limit in Ireland is low enough that guessing can easily lead to a ban.

Can a breathalyser or alcohol test be wrong?

Breathalysers, whether used by individuals or by law enforcement, are precise instruments that require proper use and regular calibration. Low‑cost devices using semiconductor sensors can be influenced by substances other than alcoholic drinks, including certain mouthwashes, breath sprays and fumes, especially if you test immediately after exposure. This is why guidelines usually recommend waiting 15–20 minutes after your last drink, cigarette or mouthwash before using a breathalyser.

Professional evidential devices used in legal contexts are based on electrochemical technology, are certified and undergo routine checks to ensure accuracy. Even so, readings taken very soon after drinking may not perfectly match blood test results, and in contested cases, blood or urine tests may be used to confirm the exact level.

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