Heavy drinking can easily leave you with blood alcohol level too high to drive legally or safely. The Fact Sheet below provides general guidance on calculating 0.00 BAC.

Many of us enjoy a good night out with good company and a few drinks. However, we need to be careful about just how much we drink and when we stop drinking because the alcohol consumed will stay with us for quite some time. Heavy drinking late into the night can easily leave you with blood alcohol levels that are too high to drive legally or safely. Drivers of trucks or buses are generally required by law to have zero blood alcohol, and your company’s policy may require zero blood alcohol of all personnel whether driving or not. This leaflet shows you a simple, easily workable method – it provides general guidance only and does not absolutely guarantee a zero BAC.

Keeping track of what we drink

A standard drink is any drink that contains 10grams of pure alcohol (equivalent to 1.25 ml) – keeping track of the number of standard drinks allows you to keep track of the amount of alcohol you have consumed. Different types of liquor contain different amounts of alcohol –the number of standard drinks equivalent to the usual measures of different types of drink is shown below. Note that a glass of wine (125 ml) contains almost the same number of standard drinks as a much larger schooner of beer (425 ml).


Allow at least one hour for your body to process each standard drink.
Suppose you have drunk 6 pots of full strength beer, equivalent to 6×1.1 = 6.6 standard drinks. If you had the last drink at 2.00pm, you may not be safe to drive until 9.00pm that day.
Remember – this is a guide only. Everybody is different and you should always allow some extra time to be safe. Trying to judge exactly how much you can get away with drinking and the latest you would have to stop drinking is a risky strategy that is inviting trouble – a crash, a drink-drive conviction or disciplinary action.

Traps and how to avoid them

There are some recognised traps to beware of – and ways of avoiding them:

  1. Losing count of your drinks – easily done when you’re enjoying the social scene, especially once you’ve had a few drinks. Set out with a clear plan to count your drinks at stick to it. Drink some water or other non-alcoholic drink between alcoholic drinks. Do not allow anybody to refill your glass until it is empty – topping up half full glasses is a sure way to lose track of what you have drunk.
  2. Losing track of time – easily done when you’re enjoying the social scene, especially once you’ve had a few drinks. Make a commitment to stop drinking at a particular time; tell the people you are with about your plan so they can remind you if need be.
  3. Glasses are often bigger than standard drinks. A frequent trap in homes, at barbecues, etc. Try to make sensible allowance for this.
  4. Alcohol can be stronger than you realise. Be aware of what you are drinking, particularly sprits with mixers. Always make sure you see how much spirit is in the glass before the mixer is added.

And finally…..

And remember, if you do get caught out and have to take sickie, give yourself time to recover before you start using power or blade tools or climb ladders!