Centre for Road Safety

Know your limit

NSW has three blood alcohol concentration (BAC) limits:  zero, under 0.02 and under 0.05. The limit that applies to you depends on the category of your licence and the type of vehicle you are driving.

Your BAC measures the amount of alcohol you have in your system in grams of alcohol per 100 millilitres of blood. A BAC of 0.05 means you have 0.05 grams (50 milligrams) of alcohol in every 100 millilitres of blood.

Zero BAC applies to all:

  • Learner drivers or riders
  • Provisional 1 drivers or riders
  • Provisional 2 drivers or riders
  • Visiting drivers or riders holding an overseas or interstate learner, provisional or equivalent licence

Learner, P1 and P2 drivers and riders are developing their driving skills. They have a zero alcohol limit because they are more vulnerable to the effects of alcohol than experienced drivers. If you are on a zero alcohol limit, you must be alcohol-free while driving or riding. This doesn’t stop you from having fun, it just means you can’t drive or ride after drinking any alcohol.

If you have been drinking, Getting back to zero explains how long it can take to get alcohol out of your system. 

Check product labels for alcohol content

Some medicines, mouthwashes and food may contain alcohol. You should check labels for alcohol content (sometimes called ethanol). All products containing alcohol can affect your BAC.

If you are going to drive, avoid these products. Otherwise you may not be able to convince a court that you didn't have an alcoholic drink or another substance for the purpose of consuming alcohol.

Religious observance

If you have a BAC limit of zero and you are caught driving with a BAC above zero, but below 0.02, and you can prove to the court that you had the alcohol as part of a religious ceremony, this will be a defence.

Under 0.02 applies to:

  • Drivers of vehicles of "gross vehicle mass" greater than 13.9 tonnes
  • Drivers of vehicles carrying dangerous goods
  • Drivers of public vehicles such as taxi or bus drivers

A BAC of 0.02 can be reached after the consumption of only one standard drink (a middy of beer, a nip of spirits or a small glass of wine). Drivers subject to a 0.02 limit should not drink any alcohol before driving.

Under 0.05 applies to:

  • ALL other licences (including overseas and interstate licence holders) not subject to a 0.02 or zero limit
  • Under 0.05 is the legal limit for most drivers

Don’t risk trying to calculate your BAC

Trying to calculate your BAC is impossible. Your BAC begins to rise as soon as you start drinking and can continue to increase for up to two hours after you have stopped drinking. Counting standard drinks to guess your BAC is difficult and often inaccurate because:

  • Alcohol concentrations vary between drinks, such as light beer (2.5%), full strength beer (5%), wine (14%) and spirits (40% or higher)
  • Beer may be served in schooners, middies and schmiddies.  Wine glasses vary in size from 100ml to 280ml or more
  • Drinks are often ‘topped up’ so it's impossible to know how many standard drinks you’ve had
  • Drinks come in non-standard sizes – many pre-mixed drinks sold in bottles or cans may contain more than one standard drink and 800ml bottles may contain three standard drinks

People are different

Alcohol also affects people differently. Two people who drink the same amount can have different BACs. This is caused by factors such as:

  • Size and weight – a smaller person will have a higher BAC from the same amount of alcohol
  • Gender – a woman the same height and weight as a man, drinking the same amount, will have a higher BAC
  • Liver function – an unhealthy liver will process alcohol slower than a healthy liver
  • Recent consumption of food – lack of food in your stomach means you will absorb alcohol into your blood faster. However, eating food after you have been drinking will not reduce your BAC
  • Fitness, fatigue and general health condition – your BAC can be higher if you are not feeling well, you are tired, stressed or unfit

We recommend that you don’t drink any alcohol if you plan to drive. Alcohol affects different people in different ways and attempting to guess your blood alcohol concentration is difficult and inaccurate.