B.A.C. – Information for Teachers & Students

Facts About Blood Alcohol Concentration (B.A.C.)

  • B.A.C. is the acronym for Blood Alcohol Concentration.

  • In Australia it is a criminal offence for an individual to operate a motor vehicle whilst under the influence of alcohol that exceeds a B.A.C. reading of:

–          0.00 for Learners (L’s) and Probationary (P’s) licence holders

–          0.05 or higher for Full licence holders

Note: There are many types of special vehicle licences. For further information please visit a local licence operator (e.g. VicRoads).

  • B.A.C. is the amount of alcohol present in an individual’s blood stream. Therefore if someone has a B.A.C. reading of 0.05 they would have 0.05 grams of alcohol in every 100 millilitres of blood.

Factors that affect an individual’s B.A.C. include:

Body Size: The bigger an individual is (either in height or weight) the more blood their body will generally contain. For example a ‘Male who is 6ft 2inc and 100kg’ and a ‘Female who is 5ft 3inc and 45 kg’ will have different amounts of blood in their bodies (Male more than Female in this example). Therefore if they consume the same amount of alcohol over the same amount of time the alcohol will be more diluted in the Male. Therefore the male will have a lower B.A.C. reading compared to the Female.

Fat to Muscle ratio: The more muscle an individual has (male or female), on average, the lower B.A.C. reading they will have. Muscle is predominately made out of water. Alcohol and water mix really well together therefore slowly releasing alcohol into the blood stream resulting in a lower B.A.C. (on average). Fat and alcohol do not mix very well together therefore releasing alcohol in the blood stream at a faster rate resulting in a higher B.A.C. (on average).

Gender: Females, on average, are smaller in height and weight compared to Males. Therefore Females are more likely to have higher B.A.C. readings in comparisons to Males.

Height: The taller an individual is the bigger their body size tends to be. Therefore taller individuals have more bloody in their bodies compared to smaller individuals.

Age: Older individuals may have sustained organ damage or organs may not function as well as they use to. Therefore organs may take a little longer in processing alcohol resulting in higher readings and alcohol remaining in the body for longer periods. If older individuals choose to consume alcohol it is recommend that they use a certified breathalyser to obtain a more accurate B.A.C. reading. Also this will allow for a greater understanding of how their body breaks down alcohol.

Time spent drinking (hrs): If an individual consumes 6 standard drinks in 2 hours and the next week they consume 6 standard drinks in 6 hours they will have a lower B.A.C. reading over the 6 hours. Remembering the amount of hours spent drinking allows for a greater understanding of estimating B.A.C.

Tip: If an individual decides to consume alcohol it is a great habit to make a note of what time they had their first drink and their last drink. Also to count how many standard drinks they consume during that period will assist in estimating their own B.A.C.

Stomach content: Eating a meal before deciding to consume alcohol allows for alcohol to be slowly released into the bloody stream. Alcohol will be absorbed into the food and release gradually into the bloody stream. Therefore resulting in a gradual increase of B.A.C. If a person consumes alcohol on an empty stomach alcohol will be released much faster into the blood stream. Therefore resulting in a faster increase of B.A.C.

  • B.A.C. and Drunkenness do not necessarily go hand in hand. For example someone who rarely drinks may have 2 standards drinks in 2 hours and appear extremely intoxicated, however they have a B.A.C. reading of 0.02. Someone of the same gender, body size and age who drinks more regularly may consume 6 standard drinks in 2 hours and not show any symptoms of drunkenness, but have a B.A.C. reading of 0.10.

  • On average, B.A.C. will not start to decline until around 1 hour after an individual stops drinking alcohol.

  • On average 0.01 B.A.C. is removed from the body every hour. Using a certified breathalyser will provide a more accurate reading of how your own body breaks down and removes alcohol.

  • For exact B.A.C. readings it is recommended that an Australian certified breathalyser be used. Visit the Blow Me First website www.blowmefirst.com.au to obtain further information on breathalysers and where to purchase Australian Certified Breathalysers.

  • Disposable Breathalysers are a fantastic way to ensure you are under the limit, especially the next day. Visit the Redline Breathlyser website www.redlinebreathalysers.com for further information. You can purchase Redline Breathalysers from the AlcoCups resources page.


Activities for increasing B.A.C. knowledge:

The ideal resource for the classroom or staff training is the AlcoCups ‘We’ve Got Your B.A.C.’ Educational Pack. The educational pack comes with detailed lesson plans (activity outline), USB contain powerpoint slides and further information and B.A.C. wallet card sheets.

Contact AlcoCups for further information or to place an order.