What is a standard drink?
A standard drink in Australia contains exactly 10 grams of alcohol. That's the number the National Health and Medical Research Council (NHMRC) uses in its official drinking guidelines, and it's the number every legal BAC limit in this country is built around.
Here's the part most people get wrong: a standard drink is not the same as a glass, a can, or a bottle. Container size and standard drink count are two completely different things. A can of full-strength beer is one standard drink of packaging. It is not one standard drink of alcohol, not even close in most cases. The gap between what you're holding and what's actually in it is exactly why standard drinks exist as a measure in the first place.
The reason the two don't match up is simple maths. Alcohol content depends on volume and strength together, and pure ethanol has a density of 0.789 grams per millilitre, meaning a millilitre of alcohol doesn't weigh a gram, it weighs less. To work out standard drinks in any drink, you need the volume in millilitres, the percentage alcohol by volume (ABV), and that density figure:
Standard drinks = (volume in mL × %ABV ÷ 100 × 0.789) ÷ 10
Run a 425mL schooner of 4.8% beer through that formula and you get roughly 1.6 standard drinks, not 1. Run a 750mL bottle of 13% wine through it and you get about 7.7, not 1. That's the whole reason a standard drinks calculator is worth using before you decide what "a couple of drinks" actually means for your body.
How many standard drinks are in common drinks?
Short answer up front: a 750mL bottle of wine at 13% ABV contains about 7.7 standard drinks, a middy or pot has around 1.1, a schooner has around 1.6, and a pint has around 2.2. Here's the fuller breakdown for drinks you'll actually order or pour.
| Drink | Typical size | Typical ABV | Standard drinks |
|---|---|---|---|
| Pot / middy (full strength) | 285 mL | 4.8% | ≈ 1.1 |
| Schooner (full strength) | 425 mL | 4.8% | ≈ 1.6 |
| Pint (full strength) | 570 mL | 4.8% | ≈ 2.2 |
| Stubby / can (full strength) | 375 mL | 4.8% | ≈ 1.4 |
| Light beer stubby/can | 375 mL | 2.7% | ≈ 0.8 |
| Glass of wine | 150 mL | 12–13.5% | ≈ 1.4–1.6 |
| Bottle of wine | 750 mL | 13% | ≈ 7.7 |
| Sparkling wine, glass | 150 mL | 11.5–12% | ≈ 1.3–1.4 |
| Spirit nip | 30 mL | 40% | ≈ 0.95 |
| RTD / premix can | 375 mL | 5% | ≈ 1.5 |
A few things worth flagging. First, "how many standard drinks in a schooner" doesn't have one universal answer, because ABV varies by beer, not just by glass size: a mid-strength schooner and a craft IPA schooner are not the same drink. The same goes for a pint: a full-strength pint is about 2.2 standard drinks, but a mid-strength pint is closer to 1.6. Second, restaurant and bar wine pours regularly exceed 150mL, so treat that row as a floor, not a guarantee. Third, if you're topping up your own glass at home, you're almost certainly pouring more than a standard drink and probably not counting it. Figures above are calculated using the standard formula (volume × ABV × 0.789 ÷ 10) and are consistent with the Alcohol and Drug Foundation's published standard drinks guide.
How many standard drinks can you have and still drive?
There is no number that guarantees you a safe BAC. That's not us being cautious, it's the honest answer, and any resource telling you otherwise is wrong.
You'll still hear the old rule of thumb: two standard drinks in the first hour, one per hour after that, to stay under 0.05. It's a rough population average, not a personal guarantee, and it breaks down fast once you look at what actually changes your BAC for a given number of drinks: body weight, sex, how much you've eaten, how fast you drank, your individual metabolism, medication, and fatigue. Two people who are the same weight and drank the same amount can land on meaningfully different readings. That's exactly why any calculator, including the one on this page, gives you an estimate to plan around, not a certificate to drive on.
If you're on a zero-BAC licence, none of this maths matters anyway. Learner, provisional (P1/P2), and most professional or heavy-vehicle licences in Australia carry a zero limit, meaning the honest answer to "how many standard drinks to drive" on those licences is zero, full stop. See the table below for exactly which limit applies to your licence in your state.
Legal BAC limits in Australia by state and licence type
Limits are broadly consistent nationwide, but the licence categories and the professional-driver limit differ by state. If you're specifically searching for a BAC calculator NSW readers can use to check where they stand, NSW follows the same three-tier structure as most other states: zero for learners and P-platers, 0.02 for certain professional drivers, and 0.05 for a full licence.
| State/Territory | Learner | P1/P2 or provisional | Full licence | Professional / heavy vehicle | Source |
|---|---|---|---|---|---|
| NSW | Zero | Zero | Under 0.05 | Under 0.02 (buses, taxis, rideshare, heavy vehicles over 13.9t GVM, dangerous goods) | Transport for NSW |
| VIC | Zero | Zero | Under 0.05 | Zero for heavy vehicle drivers | Transport Victoria |
| QLD | Zero | Zero | Under 0.05 | Zero (trucks over 4.5t GVM, buses over 12 adults, articulated vehicles, dangerous goods, taxis/limousines) | QLD Government / TMR |
| WA | Zero | Zero | Under 0.05 | Zero (taxis, buses carrying over 12 adults, vehicles over 22.5t gross combination mass, dangerous goods) | WA Road Safety Commission |
| SA | Zero | Zero | Under 0.05 | Zero (buses, taxis, heavy vehicles, dangerous goods) | SA mylicence |
| TAS | Zero | Zero | Under 0.05 | Zero (buses and vehicles over 15t gross vehicle mass) | Transport Tasmania |
| ACT | Zero | Zero | Under 0.05 | Under 0.02 (vehicles over 13.9t GVM, dangerous goods, taxis/buses) | ACT City Services |
| NT | Zero | Zero | Under 0.05 | Zero for commercial/heavy vehicle drivers | NT Government |
Limits current as at July 2026. Rules and thresholds do get amended, and heavy-vehicle definitions (gross vehicle mass cut-offs especially) vary between states, so always check your state authority above before you drive, particularly if you hold a professional or heavy-vehicle licence. If you drive for work, many Australian employers also run workplace breath testing programs with limits written into policy, which can be stricter than the licence limit.
How is BAC calculated?
Because we think a calculator shouldn't be a black box, here's exactly what's happening behind the numbers. The BAC calculator on this page uses the Widmark formula, the standard method used in alcohol research and by breath-testing science for decades:
BAC% = grams of alcohol ÷ (weight in kg × r × 10) − (0.015 × hours since first drink)
Where r is a distribution constant accounting for how alcohol spreads through body water: 0.68 for men, 0.55 for women. Women have a lower r on average because body composition differs, which means the same number of standard drinks tends to produce a higher BAC in a woman than a man of equal weight. The 0.015 figure is the average rate the body clears alcohol per hour, roughly one standard drink's worth.
Worked example: a 70kg man has three standard drinks (30 grams of alcohol) in one hour.
BAC = 30 ÷ (70 × 0.68 × 10) − (0.015 × 1)
BAC = 30 ÷ 476 − 0.015
BAC = 0.063 − 0.015
BAC ≈ 0.048
That's under the 0.05 full-licence limit, and it's also close enough to it that a slightly faster drinking pace, a lighter body weight, or an empty stomach could easily tip it over. The formula assumes alcohol is fully absorbed and evenly distributed, which takes time and doesn't happen instantly after a drink. It doesn't model food, drinking speed, or absorption delay directly, which is exactly why the Widmark equation is treated as a research and estimation tool, not a legal measurement, anywhere in Australia.
What affects your BAC?
The formula above gives you the average. Your actual BAC on the night moves around that average based on real, individual factors:
- Food. Eating before and during drinking slows absorption significantly. Drinking on an empty stomach gets alcohol into your bloodstream faster and pushes your peak BAC higher.
- Drinking speed. Four drinks over four hours and four drinks in forty minutes produce very different peak BACs, even though the total alcohol is identical.
- Body composition. Alcohol distributes through body water, not fat, so two people of the same weight but different body composition can register different BACs from the same drinks.
- Sex. As covered above, the r constant differs by sex, and hormonal factors can shift this further across a menstrual cycle.
- Medications. Some medications slow alcohol metabolism or amplify its effects. Check the label, or ask your pharmacist if you're taking anything regularly.
- Fatigue. Being tired doesn't change your BAC number, but it compounds impairment at any given BAC, which matters for judgement and reaction time even if a device would still read you as legal.
- Carbonation. Bubbles increase the rate alcohol is absorbed in the stomach, which is part of why champagne and RTDs hit faster than a still drink with the same alcohol content.
And here's the myth-busting bit, because it matters: coffee, a cold shower, exercise, vomiting, and mints do not lower your BAC. Nothing speeds up how fast your liver processes alcohol. The only thing that reduces BAC is time. If you feel more alert after a coffee, that's caffeine masking tiredness, not your BAC actually dropping.
Why a BAC calculator is only an estimate
Every input above (weight, sex, timing, drink count) goes into the same formula, but the same inputs won't produce the same real-world reading in two different people, or even in the same person on two different nights. Individual metabolism, genetics, medication, illness, and hydration all shift the actual number away from the calculated one. Research into the Widmark formula's accuracy consistently finds it can be off by a meaningful margin in either direction, which is exactly why it's used for planning and education, not enforcement.
The only way to actually know your BAC is to measure it, not calculate it. That's what a certified breath alcohol testing device does that a formula can't: it measures what's actually in your breath at that moment, rather than estimating what should be there based on averages. In Australia, the benchmark for that kind of measurement is AS 3547, the Australian Standard covering the performance, testing, and accuracy requirements for breath alcohol testing devices. A device certified to AS 3547 has been through third-party laboratory testing against that standard; a lot of cheap breathalysers on the market haven't.
If tonight's plan involves driving afterwards, use this calculator to get a sense of where you'll land, but don't use it as your final answer. Give yourself margin, or don't drive.
FAQs
How long after drinking can I drive?
There's no fixed number of hours that works for everyone, because it depends on how much you drank, your weight, sex, and how fast your body processes it. As a rough guide, the body clears about one standard drink per hour, so a big session can easily leave you over 0.05 the next morning. The only reliable way to know is to test, not guess based on a clock.
Is 0.05 the limit on my P plates?
No. In every Australian state and territory, P1 and P2 (provisional) licence holders are on a zero BAC limit, not 0.05. That means any detectable alcohol, even well under what would be legal on a full licence, is an offence on P plates.
How many standard drinks is 0.05?
There's no single answer, because it depends on your weight, sex, how long you've been drinking, and what you've eaten. As a very rough guide, a 70kg man might reach around 0.048 after three standard drinks in an hour, but a lighter person, a woman, or someone drinking on an empty stomach could hit 0.05 on fewer drinks. Use the calculator above for an estimate based on your own numbers, not a generic rule.
Can I be under 0.05 the morning after?
Not necessarily. If you drank heavily or finished late, your body may still be processing alcohol well into the next morning. Standard drinks clear at roughly one per hour on average, so a big night can leave you over the limit at breakfast time even if you feel fine.
How accurate are online BAC calculators?
They're estimates built on population averages, not measurements of you specifically. The Widmark formula behind most calculators, including this one, has a documented margin of error because it can't account for your exact metabolism, stomach contents, or absorption speed on the night. Use it to gauge roughly where you stand, not as proof you're under the limit.
What BAC will a breathalyser show vs this calculator?
A certified breathalyser measures the alcohol actually in your breath at that moment. This calculator estimates what your BAC should be based on averages for your weight, sex, and drinks. The two can differ, sometimes by a meaningful margin, which is exactly why a calculator is a planning tool and a certified device is a measurement.
What counts as a standard drink for the calculator?
10 grams of alcohol, the same definition NHMRC uses in the national drinking guidelines. It's not tied to glass size or container, which is why a single wine glass or beer can often adds up to more than one standard drink. See the table above for common examples.
Do the NHMRC guidelines mean up to 4 drinks a day is safe?
No. The 2020 NHMRC guidelines recommend healthy adults have no more than 10 standard drinks a week and no more than 4 on any single day, to reduce lifetime risk of alcohol-related harm. That's a risk-reduction ceiling, not a daily target, and it says nothing about what's safe for driving, which is a separate and much lower threshold.
References
- National Health and Medical Research Council (NHMRC). Australian Guidelines to Reduce Health Risks from Drinking Alcohol (2020). nhmrc.gov.au
- Alcohol and Drug Foundation. A Guide for Counting Your Drinks. adf.org.au
- Transport for NSW / NSW Government. Alcohol limits, drugs and medicines. nsw.gov.au
- Transport Victoria. Alcohol and driving laws. transport.vic.gov.au
- Queensland Government / Department of Transport and Main Roads. Blood alcohol limits. qld.gov.au
- WA Road Safety Commission. Drink and drug driving. wa.gov.au
- Government of South Australia. The Driver's Handbook: Alcohol. mylicence.sa.gov.au
- Transport Tasmania. Licence conditions. transport.tas.gov.au; Road Safety (Alcohol and Drugs) Act 1970. legislation.tas.gov.au
- ACT Government / City Services. Drink and drug driving. cityservices.act.gov.au
- Northern Territory Government. Alcohol, drugs and driving. nt.gov.au
- Austroads. Drivers' legal BAC limits. austroads.gov.au
- Standards Australia. AS 3547 Breath alcohol testing devices. standards.org.au