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How many standard drinks to .05?

How many standard drinks to .05?

Anyone licensed to operate a vehicle in Australia should know how many standard drinks it would take to reach 0.05. This seemingly innocent decimal should trigger a panic button response in drivers.

After all, the legal limit of alcohol content in the bloodstream in Australia is below 0.05%BAC, and the consequences of getting caught are getting tougher and tougher as drink driving statistics show little improvement with each passing year.

Whether or not you are familiar with the legal impairment limit, it is crucial that you are responsible for your own personal tolerance level. Understanding your own limit begins with eradicating your mind of any clichés you’ve heard before.

More importantly, understand that intoxication begins with just one drink. You may be below 0.05%BAC, but you may still be incapable of operating a vehicle safely and can be arrested for compromising the safety of others.

Read on to find out how many drinks it would take you to reach 0.05%BAC.

Know what is a standard drink

Before we figure out how many standard drinks it would take to reach .05, we must start with understanding what’s a standard drinkIn Australia, a standard drink is one that contains 10 grams (about 12.5ml) of alcohol.

For other countries, this may be different. For example, in the UK, the standard is 8 grams (10ml) of alcohol.

So if you’re in Australia, just remember the magic number – 12.5.

Calculate how many standard drinks you've consumed

Alcoholic beverages include a label noting the percentage of alcohol by volume (e.g. 5%).

Therefore, to calculate how many standard drinks a beverage has would involve some simple math.

For example:

A 375ml bottle of mid strength beer (2.7% alcohol)
Alcohol content = 375 x 0.027 = 10.12ml alcohol
Standard drinks = 10.12ml ÷ 12.50ml = 0.81 standard drinks
A 150ml glass of wine (11.5% alcohol)
Alcohol content = 150 x 0.115 = 17.25ml alcohol
Standard drinks = 17.25ml ÷ 12.50ml = 1.38 standard drinks


Estimate how many standard drinks it'll take you to reach 0.05

After you’ve calculated how many standard drinks your beverage contains, you can start to estimate your own BAC and figure out how many drinks it would take to reach .05.

Also, note that even if someone else drinks the same drinks as you, it does not mean that they will have the same BAC as you. 

Remember that there are many factors that affect blood alcohol level (BAC) so you will have to test out the methods below to get an estimation.

Here are the most common estimation methods to know how many standard drinks it would take for one to reach the Australian legal limit of 0.05.

Ways to figure out how many standard drinks to .05


The more you drink, the more drunk you feel. You may notice feeling more noticeable effects of alcohol on the body the more you drink. This may include mood swings, slurred speech, less inhibition, and worst of all, unsound judgement (I’m sure many of us have woken up the next day thinking, “why did I do that?!”).

The obvious thing to do is to not get behind a wheel and drive, but catch a cab home or hitch a ride from someone sober. But that decision isn’t that easy when you’re already not thinking too clearly.

That said, self-assessment is the poorest and least reliable method of estimating your BAC.

Drinks per hour rule

The general rule of thumb is that 2 standard drinks in the first hour will raise your BAC to 0.05%, and 1 standard per hour thereafter will maintain that level.

To do a quick calculation of whether you are over 0.05% BAC, simply take the number of hours since your first drink and add 1 to it. This is the number of standard drinks that you could safely have in that period.

Then, calculate the number of standard drinks that you actually had, and compare the two results.

This method seems easy enough, and is free and convenient, too. But not all drinks are equal. Wine, beer and spirits all have varying alcohol concentrations, and the strength of a mixed drink can fluctuate radically based on who is doing the mixing.

When combined with poor drunken judgement, it makes calculating your BAC based on the number of drinks per hour extremely inaccurate.

BAC Calculators and Charts

With access to the web and smartphone apps, there’s little excuse to be uninformed about monitoring blood alcohol content (BAC).

There are, after all, a plethora of free resources geared towards helping consumers calculate their BAC levels.

These sites and apps have BAC calculators and charts that are very user-friendly and make calculations based off a series of step-by-step questions. These questions usually include your age, gender, weight, alcohol strength, and alcohol consumption.

However, complete reliance on BAC calculators and charts is not a safe and reliable strategy. In fact, it could give a very inaccurate calculation as it omits important factors that affect blood alcohol level (BAC) and other medical-related information. For example, your metabolism, drug interactions and food consumption prior to the test can have a profound effect on the measurement.

So BAC calculators and charts may give you what seems like an accurate BAC estimation, but can in fact be totally off the mark.

Alcohol breath testers

If you've ever been stopped by the police before for a Random Breath Test (RBT), you'd already be familiar with alcohol breath testers. Also known as breathalysers, they are what the police use to breath test drivers for alcohol. A breathalyser works by measuring your breath alcohol level, which is related to your blood alcohol level. It then provides a digital reading for you in BAC format.

Why leave it to chance? Invest in a personal breathalyser today

Out of all the methods to estimate your BAC above, a breathalyser is the most reliable solution that takes a measurement directly from your breath sample. More importantly, it is not based on estimations and calculations of standard drinks and hours passed. Although not as accurate as a blood test, there is no other method that is as fast, convenient and reliable for an immediate alcohol breath test.

It is a good idea to invest in a good alcohol breath tester or breathalysers if you are a regular drinker. It is, after all, what the police would use to test you during an RBT. 

Today, you can purchase a range of accurate and certified personal breathalysers that are portable, easy to use, and use fuel cell sensor technology that are just as accurate as police breathalysers. With proper maintenance, a breathalyser can last up to a lifetime and are certainly worth the investment to help you check your BAC. 

There can’t be enough emphasis on the quality of a device. After all, a 0.01% discrepancy in BAC detection accuracy can spell the difference between life, death, injury, or a hefty fine and prison sentence. Therefore, be wary of the breathalyser and company that you are purchasing from. Invest in a breathalyser that is certified, reliable, and has local calibration services to keep your device properly maintained throughout its lifetime. 

So now that you know about the different ways to find out how many standard drinks to .05, you can be more informed the next time you’re out drinking.


Whether you’re drinking one standard drink or two, remember that a wide range of factors can influence your BAC. Therefore, if you drink, it’s best not to drive.

If you want to be extremely sure, invest in a quality breathalyser and test yourself before the police test you.

Check out the complete infographic below.