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When can you drive after drinking alcohol?

When can you drive after drinking

Asking yourself “When can I drive after drinking?” is likely to be an indication that you are not fit to drive.

A study by the Transport Accident Commission found that around 1 in 5 drivers and riders that are involved in fatal crashes were found to have a Blood Alcohol Content (BAC) above the legal limit of 0.05. 

To better gauge when you can drive after having a few drinks, it’s important to understand how alcohol affects your body, how it’s metabolised and the best methods to determine your level of impairment.

What is alcohol?

Ethanol, a kind of alcohol is the key ingredient in alcoholic beverages. It’s produced through the fermentation of grains, fruits and other sources of sugar.

Ethanol acts as a drug that provides feelings of relaxation and happiness when consumed in moderation but can also have adverse effects.

Apart from being the most widely used social drug in Australia, alcohol is also a depressant that slows down your responses, and affects the way you think, feel and behave.

The effects of alcohol on your body

How much alcohol affects you depends on how many standard drinks you have downed at a given time.

It’s also important to note that the effects of alcohol vary from person to person depending on genetics, age, gender, body weight and more. The Australian Department of Health and Aged Care outlined some effects of alcohol consumption that include:

  • Increased feelings of confidence
  • Impaired balance, coordination, motor skills, judgement
  • Unstable emotions
  • Slower reaction times
  • Reduced inhibitions
  • Nausea and vomiting
  • Slurred speech

A research on the effects of low doses of alcohol on driving skills showed that even a BAC of 0.0018 can cause impairment. The likeliness of accidents can happen to you, your passengers, or to innocent strangers when you underestimate the effects of alcohol on you.

By understanding how to measure your BAC and how your body metabolises alcohol, you could prevent any unfortunate incidents and contribute to safer Australian roads.

Check your BAC

The easiest and most accurate way of calculating your BAC is through the use of a breathalyser. However, if one is not at your disposal, there are a few other ways to roughly estimate your BAC:

Online calculator

Online BAC calculators take into account how many drinks you’ve had, how you’ve been drinking, weight, gender and other factors before coming up with an estimated BAC reading.

BAC chart

Similar to the online calculator, a BAC chart analyses similar factors mentioned above and comes up with an estimated reading. 

Count your standard drinks

1 standard drink is equivalent to about 10 grams of alcohol or about 500ml of mid-strength beer (2.7% alcohol). Generally, 2 standard drinks in the first hour can raise your BAC to .05%BAC.


The more you drink, the more impaired you will feel. Take note of these impairments to estimate how drunk you feel and whether or not you feel okay to drive. However, as the effects of alcohol kick in, you may begin to feel overconfident and inadvertently underestimate how drunk you really are.

Take an alcohol breath test

The easiest and most accurate way to check your BAC level is by using a personal breathalyser to check your alcohol level.There are different kinds of breathalysers depending on your preferences and budget, and they are worth the investment to estimate your BAC so you can make an informed decision.

There are many factors involved in how alcohol affects your body with every person reacting to alcohol differently. More importantly, note that even a little bit of alcohol alters your ability to react and make decisions. The best time to drive is when you have zero alcohol in your system.

How alcohol is metabolised

Bowling Green State University explained the science behind alcohol metabolism, highlighting the importance of the liver in producing enzymes that dehydrogenase alcohol, eventually breaking them down into ketones to bring your BAC down by about .015 per hour.

It is important to note that alcohol affects each person differently. Two people can drink the same amount of alcohol but have different BACs. Factors such as weight, gender, height, and liver health can affect how the body processes alcohol.

Some drinks can impair people faster than others depending on their respective alcohol content. That’s why it’s crucial to know how many standard drinks you consume each time.

Additionally, the factors mentioned above can significantly affect your metabolic rate, thus extending the duration of your impairment. It takes up to 18 hours for your BAC to drop to 0, so you could still record a BAC of 0.05 or more the morning after.

Drinking litres of water combined with rest and coffee will not speed up alcohol’s exit from your body. Avoid believing in these alcohol myths and instead, know your alcohol facts to make smarter and more responsible decisions when it comes to drinking alcohol.

However, remember that different drinks contain different amounts of alcohol, so it’s essential to know how many standard drinks you consume each time.

Additionally, the factors previously mentioned can greatly affects one’s metabolic rate, thus extending the number of hours they shouldn’t drive for.

It takes up to 18 hours for your BAC to drop to 0, so you could still record a 0.05%BAC or more the morning after.

Drink driving laws in Australia

In Australia, the legal limit for most drivers is above 0.05 %BAC while L and P licence holders need to have a BAC of zero. It’s also worth noting that blowing under the legal limit on your breathalyser doesn’t mean that you are safe to drive.

Drink driving offences in Australia vary from state to state but are considered serious offences no matter where you are in the country. Generally, a person caught driving above the BAC limit will face a licence disqualification of up to three years and hefty fines of up to $3,859. An alcohol interlock may also be ordered to be installed in the offender’s motor vehicle. 

When can I drive after drinking?

When asking yourself “When can I drive after drinking?”, consider the factors discussed above. Understand that it’s not just the number of hours that tell you how long after drinking you can drive, but whether there is still alcohol in your system that will influence your ability to drive. Remember that even a little bit of alcohol can affect your ability to drive safely.

Breathalysers, BAC calculators, and understanding your body’s alcohol metabolism are only guides. These tools are there to help you estimate the alcohol content in your system, but they are not tools to drink and drive.

Remember that driving under the influence of alcohol can lead to trouble with the law and cause harm to innocent people, yourself and your loved ones. It’s safest to drive when you have zero alcohol in your body.