Drink Driving Limit: How Long After Drinking Can I Drive?

Australians are a social bunch. Enjoying the beautiful weather around a barbecue with friends is part of our culture. On such occasions, you might have a drink or two.  

Then, there’s the task of getting home. We know that driving drunk is an absolute no-go, but if you’ve had just a couple of drinks spread over several hours, you might have contemplated getting behind the wheel. 

At some point, all drivers have wondered how long after drinking can I drive?

As we head into the silly season — where drinks are flowing and parties are in full swing — it’s especially important to solidify our understanding of drink driving rules in Australia. 

This guide unpacks everything you need to know about the drink-driving limit so that you can help to keep our roads, and everyone on them, safe.

What Defines Drink Driving?

There are two types of drink-driving offences.

One is exceeding the Prescribed Concentration of Alcohol (PCA), and the other is Driving Under the Influence (DUI). 

Exceeding the PCA is the most common form, and these cases are usually identified during routine police breath testing. 

DUI describes the impaired ability to control a vehicle.

What Does BAC Stand For? 

The BAC refers to Blood Alcohol Content. 

It describes the limit of how much alcohol can be present in a person’s blood in order for them to safely operate a vehicle.  

What is the Legal Drink Driving Limit?

For full licence holders, the maximum BAC is 0.05%.

For learners, provisional and probationary licence holders, taxi and bus drivers, and drivers operating vehicles over 15 tonnes, any measure of alcohol in the blood is a breach of licence conditions. Your BAC must be 0.00%. 

When Can I Drive After Drinking?

So, now comes the question most of us have asked ourselves at some point: how long after drinking can I drive in Australia?

Unfortunately, there’s no straight answer. There are a number of different factors that determine your BAC and how quickly you metabolise alcohol, including

• Your sex
• Your weight
• Your age
• What type of drinks you consumed
• What you’ve eaten
• How much you’ve eaten
• Supplements or medications you're taking
• Fitness levels

For this reason, there is no prescribed ‘wait time’ between drinking and driving that guarantees a safe BAC level. 

Small amounts of alcohol leave the body in urine, breath, and sweat. A healthy liver will break down less than one standard drink per hour, but if your liver is damaged, this can take longer. 

Have you ever heard that coffee, showers, water, and food can help sober you up? While they may make you feel better, these remedies will not change your BAC levels. Time is the only thing that can do that.

After a heavy night of drinking, it can take over 18 hours for your BAC to fall back to zero. In fact, many people are charged with drink driving offences the day after a night out. 

How Long After Drinking Can I Drive on P Plates?

If you’ve recently graduated from a learner’s licence to a probationary licence, you’ll be relishing the freedom of driving without a supervisor or instructor.

However, there are still a number of rules and restrictions you must abide by when holding a probationary licence. 

A probationary licence does not come with the same BAC permissions as a full licence. Your BAC must be 0.00% when holding a learner’s or probationary licence.

That means you may not, under any circumstances, consume an alcoholic beverage and then drive. 

How Many Drinks Can You Have and Drive?

The number of drinks you can have before driving will differ from person to person, depending on the various factors mentioned earlier. 

Unfortunately, there’s no one answer to this question. 

The only way you can be sure you won’t be driving above the 0.05% limit is not to drive after drinking. 

How Many Drinks is 0.05? 

Many people operate under the generalised rule that 2 standard drinks in the first hour will raise your BAC to 0.05%.

This rule of thumb also states that a standard drink for each subsequent hour will maintain your BAC at 0.05%. Any more than that, and your BAC will rise above the 0.05% legal limit. 

However, it’s important to remember that this rule is oversimplified. 

As mentioned, various factors determine the way your body absorbs and responds to alcohol. 

Additionally, alcohol concentrations vary between drinks. For example, 40% proof Vodka will increase your BAC faster than a 4% beer. Serving sizes also act as another variable, and pre-mixed drinks complicate things further.  

Consider this; how can you calculate the number of standard drinks you consumed from a shared bottle of wine? What about the drink you took just a few sips of? Do you know how much vodka was in the drink your friend mixed for you?

Counting drinks is not a safe or reliable way to determine whether or not you can drive. 

How Long Does Alcohol Stay in the Blood?

Generally, it takes the body around an hour to process one standard drink. 

However, two people can consume the same amount of alcohol and produce different BACs due to the aforementioned factors that influence how alcohol is absorbed into the body.  

Blood Alcohol Calculator

There is a range of BAC calculators online that can be used to give you a rough estimate of your BAC levels. 

Keep in mind that these calculators only provide estimates and cannot guarantee 100% accuracy. Under no circumstances should these calculators be used to determine whether or not you should get behind the wheel.

You can also purchase breathalysers from a variety of online websites and car accessory stores. If the price for the device seems too good to be true, it probably is; the technology in cheaper versions is likely dated and inaccurate. 

If you’re going to purchase a breathalyser to get an idea of your BAC levels, opt for a device from a reputable brand. Even still, the results from these devices will not be as accurate as the results from the official police BAC reader.

A calibrated testing machine is the only way to measure your BAC accurately. 

The only way to ensure you are under the legal limit is to follow this simple rule: if you are going to drink, do not drive. 

For the safety of yourself and other road users, if in doubt, sleep it out. 

What’s the Penalty for Drink Driving?

Laws and penalties vary from state to state.

If convicted of an offence, the court will revoke your licence for a certain amount of time, depending on; your level of intoxication, other offences, and if you’ve had a prior history of drink-driving.

Once their licence has been returned, anyone who has committed a drink-driving offence must install an alcohol interlock into their vehicle for a set period. 

Fully-licenced drivers who measure a BAC of between 0.05 to 0.07% will receive a fine and incur 10 demerit points. For drivers who record a BAC over 0.07%, the licence will be cancelled, and they will need to install an interlock for at least six months when relicensed. 

Repeat drink drivers will have their licence cancelled and are required to install an interlock.

Learner and probationary drivers who have a BAC below 0.05% will have their licence cancelled for three months. They will also need to install an interlock for at least six months when they are licensed. 

Remember, the consequences of losing your licence are significant. For many people who require a car for work, this can result in a loss of employment. 

In some cases, a drink-driving offence can lead to prison time. 

As of 2011, it is also an offence to drink alcohol while sitting next to a learner driver, even if there is no alcohol in the driver’s breath or blood. 

Don’t Risk It 

The only way to ensure you’re not driving over the Australian drink driving limit is not to drive after drinking any amount of alcohol. 

There is no one answer to the question of how long after drinking can I drive, so your best bet is to exercise an abundance of caution.

If you’re planning to drink, rope in a mate to be the designated driver, or catch an uber or taxi home. 

No night out is worth risking a life.