Australia is a wonderful place.

Beaches.

Prawns on the BBQ.

And, of course, beer.

Of course, we can predict with absolute certainty that the Queensland Police Service will be out conducting random breath tests on any day we happen to available ourselves of said beers.

So, without wanting to be too preachy, let’s take a look at a few dos and don’ts if you’ve got a few cold ones in mind and need to drive home afterwards.

Understand the Risks

We’ve written about these before, but essentially drink driving offences in Queensland are split into three categories:

1. Over 0.05 Blood Alcohol Concentration (BAC) but under 0.10 – low range drink driving
2. 10 BAC and over, but under 0.15 – mid range drink driving
3. 15 BAC and over – high range drink driving.

Read the articles for the specifics, but depending on your situation in every case you are at risk of:

1. Licence suspension or disqualification;
2. Fine;
3. Potentially imprisonment in significant situations.

At a level closer-to-home, you will also probably have to explain to your family, employer and friends why you can’t drive anywhere at the moment.

So let’s just avoid all those things.

Understand How BAC Works

While it varies from person to person, your blood alcohol concentration at any given moment is going to depend on these major factors:

1. How much you have had to drink;
2. How long you have been drinking;
3. Your gender;
4. Your weight.

Of course, various medical conditions and personal circumstances can affect this also, but factors tend to be a decent rule of thumb according to most guidelines.

So for example, a 100kg man who has had 4 drinks over 2 hours is typically going to have a lower BAC than a 50kg woman who has had 4 drinks in 2 hours.

Understand What You’re Drinking

Most people already know that alcohol consumption is measured in “standard drinks”, which is always equal to 10g of pure alcohol.

As a result, most of our rules of thumb tend to revolve around how many standard drinks you have had.

The problem is: there is no real standard when it comes to what you’re likely to buy. Wines are different in alcohol content and glass sizes, as are beers and basically everything else.

This is where a lot of people come unstuck. It’s the “I only had one glass of wine” problem, not recognising the 1 glass of wine is sometimes under 1 standard drink, and 1 glass of wine other times might be 2.5 standard drinks.

There are two relevant considerations:

1. How much alcohol is in the thing you’re drinking; and
2. How much of it are you drinking.

These can be HIGHLY variable.

So for example:

1. A large glass (425ml – a schooner in most places) of full strength beer at 4.8% will be 1.6 standard drinks;
2. A schooner of low strength beer at 2.7% will be 0.9 standard drinks.

Similarly:

1. A “normal” glass of wine at 100ml and 13.5% alcohol will be around 1 standard drink; but…
2. Many restaurants will serve you a 150ml glass, which turns it instantly into around 1.6 standard drinks (rounded up, if you’re wondering about the obviously wrong maths there).

This, of course, makes a massive difference to how much alcohol you have actually consumed with your mates after work.

So while we’re not suggesting you should give up social time to examine every bottle with a magnifying glass before enjoying your beverage, it leads to two basic ideas:

1. Know roughly what you’re drinking and how much alcohol it has in it;
2. Know roughly how much of it you’re drinking. This is obviously easier if you’re drinking cans or bottles, but gets trickier with poured drinks in glasses of different sizes, especially with a “top up” here and there.

Some Worked Examples

We’ve run a few simple examples through the BAC calculator here (no endorsement – we just Googled it).

Adam is a 100kg male who has 3 schooners of heavy beer in a 1 hour sitting after work. While Adam may not be that behaviourally impaired, Adam’s BAC is likely 0.6 and Adam will be at over the legal limit to drive and should wait before getting behind the wheel. Adam’s BAC will be 0 again in 4 hours.

Jennifer is a 55kg female and goes “round for round” with Adam – 3 schooners of heavy in 1 hour. Jennifer’s BAC is 0.134 – clearly MUCH higher than Adam’s. It will take Jennifer just under 9 hours to get a 0 reading again, and Jennifer should probably be getting an Uber once she’s satisfied she won’t vomit in the Uber

Michael is a 60kg male who has 3 “glasses” of wine in 2 hours, but didn’t pay attention to anything else. As it turns out, they were over-pouring already large glasses, and Michael has effectively had 5.4 standard drinks. Despite “only” having three glasses in two hours, Michael’s BAC is .096 – nearly double the legal limit to drive. Michael will have a 0 BAC in around 6.4 hours.

As you can see, the main variables of each person, drink type and drink size make a huge difference to the overall outcome.

Be Safe

There are far worse things that can happen on the roads than losing your licence, and if you’re reading this we don’t want any of those to happen to you.

Understanding the principles we’ve set out above, and applying a healthy dose of common sense should have you driving safely for many years to come.