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New Zealand

Blood Alcohol Calculator NZ – Standard Drinks & 0.05% Limit 🇳🇿

Calculate your estimated Blood Alcohol Concentration (BAC) instantly. Track standard drinks, view sobriety charts, and check your status against New Zealand's 0.05% legal limit (zero tolerance under 20).

0.05% BAC Legal limit

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Drink Driving in New Zealand — 0.05% BAC

Drivers aged 20 and over must stay under 250mcg of alcohol per litre of breath (50mg per 100ml of blood), equivalent to 0.05% BAC. Drivers under 20 have a zero alcohol limit — any alcohol is an offence. Compulsory Breath Testing is enforced by NZ Police nationwide.

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 — driving is illegal. Close to the legal limit — this estimate could already be over. Below the legal limit — not the same as safe to drive.
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Sober in: {{ sobrietyTime }}

Drink Driving in New Zealand

Drivers 20 & over 0.05%
Drivers under 20 0.00%

Common Penalties in New Zealand

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 Infringement offence 250–400mcg breath / 50–80mg blood (drivers 20+, infringement) Administrative offence — fine and licence points possible.
Typical penalties
  • $200 infringement fee and 50 demerit points
  • No court appearance or conviction in this band
  • Drivers under 20: $200 + 50 points for any alcohol; criminal charge above 150mcg / 30mg
Offence type Criminal offence (court) Over 400mcg breath / 80mg blood (court) Criminal offence — may result in a criminal record.
Typical penalties
  • Criminal conviction — fine up to NZ$4,500 and/or up to 3 months imprisonment (first offence)
  • Mandatory disqualification of 6+ months
  • Repeat offences: up to NZ$6,000, 2 years imprisonment and an alcohol interlock
These are general penalties. Actual consequences may vary by local law and circumstances. Learn more →

Legal limit

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Based on NZ law ·

Elimination rate

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Assumed average

Standard Drinks

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Approx. consumed

Pure Alcohol

{{ results.length > 0 ? results[0].pureAlcoholMl : '0' }} {{ qunits }}
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 — driving is illegal. Close to the legal limit — this estimate could already be over. Below the legal limit — not the same as safe to drive.
{{ legalLimitTimeLabel }}
Sober in: {{ sobrietyTime }}

Drink Driving in New Zealand

Drivers 20 & over 0.05%
Drivers under 20 0.00%

Common Penalties in New Zealand

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 Infringement offence 250–400mcg breath / 50–80mg blood (drivers 20+, infringement) Administrative offence — fine and licence points possible.
Typical penalties
  • $200 infringement fee and 50 demerit points
  • No court appearance or conviction in this band
  • Drivers under 20: $200 + 50 points for any alcohol; criminal charge above 150mcg / 30mg
Offence type Criminal offence (court) Over 400mcg breath / 80mg blood (court) Criminal offence — may result in a criminal record.
Typical penalties
  • Criminal conviction — fine up to NZ$4,500 and/or up to 3 months imprisonment (first offence)
  • Mandatory disqualification of 6+ months
  • Repeat offences: up to NZ$6,000, 2 years imprisonment and an alcohol interlock
These are general penalties. Actual consequences may vary by local law and circumstances. Learn more →
{{ afterLabel }} {{ $t('unit.' + units) }} Status
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  • Below the legal limit — not the same as safe to drive.
  • Close to the legal limit — this estimate could already be over.
  • Above the legal limit — driving is illegal.

This is general information, not legal advice, and the estimate is approximate. The only safe level before driving is zero.

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Sobriety Over Time

Your estimated BAC as your body clears the alcohol

Sober in {{ sobrietyTime }}
  • {{ lookaheadBacDisplay }}{{ unitSign }} Above the legal limit — driving is illegal. Close to the legal limit — this estimate could already be over. Below the legal limit — not the same as safe to drive.
  • {{ $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 share of alcohol in your blood right now, shown as a percentage. New Zealand law also states the limit in breath (micrograms per litre) and blood (milligrams per 100 ml); this figure is the blood-percentage equivalent that a Compulsory Breath Test converts to.

Legal limit

Drivers aged 20 and over must stay under 0.05% BAC — 250 micrograms per litre of breath, or 50 mg per 100 ml of blood. Drivers under 20 have a zero limit: any alcohol at all is an offence. NZ Police run Compulsory Breath Testing nationwide, and going over brings infringement fees, 50 demerit points, court fines and disqualification.

Elimination rate

Your body works alcohol off at a fairly fixed rate — about 0.015% BAC an hour — and there is no way to rush it. A feed, a coffee or a good sleep can make you feel better while the reading itself falls no faster, so a big night out can still leave you over the limit at breakfast.

Standard Drinks

A New Zealand standard drink is 10 grams of pure alcohol. Everyday servings hold more than one: a 330 ml can of 5% beer is about 1.3 standard drinks, a large 745 ml bottle around 2.9, and a restaurant pour of wine often 1.5. This total tallies them up so serving size does not catch you out.

Pure Alcohol

The pure alcohol (in grams) your body has taken on so far — the figure your standard-drink count and BAC are both worked out from.

Time vs. Sobriety Table

The table maps your BAC hour by hour. Add the time of your first drink and the estimates line up with the clock, so you can see when you should drop back under 0.05% (or under zero, if you are under 20). Status icons show which hours are safe to drive; leave the time out to read it in hours elapsed.

Sobriety Over Time Graph

A line chart of your BAC easing off over the hours ahead, showing when it slips below the legal limit and below a genuinely safe level.

How Alcohol Affects You

A reference table pairing BAC ranges with their usual effects on judgement, coordination and reaction time — effects that set in well before the limit.

Legal limit reached in / Sober in / Peak BAC

Quick summary estimates:

  • Legal limit reached in: time until your BAC drops below 0.05% (or zero for under-20 drivers).

  • Sober in: time until it returns to ~0.000%.

  • 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 New Zealand drink?

Alcohol consumption per adult, per year

9.2L

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

Per adult, that is roughly:

418 beers ≈ 8/week
511 glasses of wine ≈ 10/week
575 shots ≈ 11/week
9.2 L
0.1 L Ø 4.2 11.2 L

121% above the regional average

Ranks #4 of 25 in Western Pacific Ranks #39 of 188 in the World Average in Western Pacific: 4.2 L

How neighbours compare

#1 Australia 11.2L #1 Western Pacific
#2 United Kingdom 10.9L #18 Europe
#3 United States 9.8L #3 the Americas
#4 New Zealand 9.2L #4 Western Pacific
#5 Thailand 7.6L #1 South-East Asia
#6 Japan 6.3L #7 Western Pacific

How safe are the roads in New Zealand?

Road traffic deaths per 100,000 people, per year

6.6 /100k

road traffic deaths per 100,000 people, 2021

~44% of road deaths linked to alcohol WHO estimate, 2019 · 31–57%
7 road deaths per week WHO estimate, 2021
3 alcohol-linked deaths per week WHO-derived estimate
6.6
0.0 Ø 10.8 22.2

39% fewer road deaths than the regional average

#8 safest of 28 in Western Pacific #46 safest of 195 worldwide Average in Western Pacific: 10.8 per 100k

How neighbours compare

#1 United Kingdom 2.4 #6 Europe
#2 Japan 2.7 #3 Western Pacific
#3 Australia 4.5 #5 Western Pacific
#4 New Zealand 6.6 #8 Western Pacific
#5 United States 14.2 #20 the Americas
#6 Thailand 25.4 #8 South-East Asia

Latest available year shown per country.

LIMITS NEARBY

BAC limits in neighboring countries

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

AU

Australia

0.05%
Moderate
UK

United Kingdom

0.08%
Relaxed
US

United States

0.08%
Relaxed
JP

Japan

0.03%
Strict
TH

Thailand

0.05%
Moderate

Drink Driving in New Zealand

Legal alcohol limits for New Zealand drivers

Drivers 20 & over
0.05%
Moderate
Drivers under 20
0.00%
Zero tolerance
Drivers aged 20 and over must stay under 250mcg of alcohol per litre of breath (50mg per 100ml of blood), equivalent to 0.05% BAC. Drivers under 20 have a zero alcohol limit — any alcohol is an offence. Compulsory Breath Testing is enforced by NZ Police nationwide.

Common Penalties in New Zealand

Consequences of exceeding the legal alcohol limit

250–400mcg breath / 50–80mg blood (drivers 20+, infringement)
Infringement offence
  • $200 infringement fee and 50 demerit points
  • No court appearance or conviction in this band
  • Drivers under 20: $200 + 50 points for any alcohol; criminal charge above 150mcg / 30mg
Over 400mcg breath / 80mg blood (court)
Criminal offence (court)
  • Criminal conviction — fine up to NZ$4,500 and/or up to 3 months imprisonment (first offence)
  • Mandatory disqualification of 6+ months
  • Repeat offences: up to NZ$6,000, 2 years imprisonment and an alcohol interlock

Source: NZ Transport Agency / NZ Police.

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: Health New Zealand / NZ Transport Agency.

Official sources & references

The limits and penalties on this page come from official government sources

Confirm the current rules directly with the responsible authorities:

Laws change — always check the latest limits and penalties with the official source before driving.

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?

As a rough guide, your body clears alcohol at about 0.015% BAC per hour, and this pace cannot be hurried. That means a heavy session takes a long time to clear: if you go to sleep with a BAC around 0.15%, it can take 10 hours or more to return to zero. This is exactly why so many drivers are caught "the morning after", still over the limit on the drive to work.

How long alcohol stays detectable also depends on the test. In breath and blood it tracks your current BAC and fades over hours; in urine, specialised EtG tests can pick up alcohol for a day or more; and hair testing can indicate use over months. For driving, the figure that matters is your current BAC — and the only safe number before getting behind the wheel is 0.00%. Use the calculator to estimate your own time to zero.

How can I lower my BAC?

The honest answer is that you cannot actively lower your BAC — only time does that. Once alcohol is in your bloodstream, the liver removes it at a steady rate of roughly 0.015% per hour, and no trick changes that pace. Vomiting may clear alcohol that is still in your stomach and not yet absorbed, but it does nothing about the alcohol already in your blood. Water helps with dehydration and hangover symptoms, but it does not "flush" or dilute alcohol out of your system any faster.

Coffee, cold showers, energy drinks, fresh air and exercise are all in the same category — they may make you feel sharper, but your BAC is unchanged, which makes them genuinely dangerous if they convince you that you are fit to drive. There is no shortcut. If your BAC is up, the only safe plan is to wait it out and not drive until enough time has passed.

How accurate are breathalyzers?

No breathalyzer is perfectly precise — every device has a margin of error. Police are aware of this: roadside units are used as a screening tool, and any positive result is confirmed with a more accurate evidential test on a calibrated instrument, which is what carries weight as evidence.

Personal breathalyzers vary enormously in quality. A certified device with a fuel-cell sensor can give a reasonable indication, but a cheap keychain tester can be wildly inaccurate and should never be used to decide whether you are fit to drive. Readings also drift if a device is not regularly calibrated, or if you test too soon after a drink, when mouth alcohol can inflate the result. Treat any personal device as a rough guide only — if a reading is anywhere near the limit, the safe choice is not to drive.

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