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How long does alcohol stay in your body?

How long does alcohol stay in your body?

If you’re someone that enjoys a few drinks on the weekends and often drives, it’s essential to know and understand how long alcohol stays in your system and how it affects your body.

It is a common misconception that a person would be safe to drive if they wait a few hours after drinking, but the truth is that the rate of alcohol metabolism is dependent on a few different biological factors as well as the strength of alcohol consumed. A general rule of thumb is that blood alcohol content (BAC) declines at a rate of .015% per hour.

However, factors like age, gender, body fat percentage, genetics, and others play a role in how long alcohol stays in your system. The best way to accurately estimate your BAC level to make better decisions is through the use of a breathalyser.

Here, we discuss how long alcohol will stay in your system, how long it will take to recover from a hangover and when you can start driving again.

How long does alcohol stay in your system?

Alcohol can stay in your system for up to 12 hours depending on the factors above, including age, gender, nutrition before drinking, and amount of standard drinks consumed will affect how long alcohol stays in your system.

Using the generally accepted rule of thumb that a person’s BAC declines at a rate of .015% per hour, it can take over three hours for a person’s BAC to reach zero if their blood alcohol content was at .05 after drinking.

Keep in mind that a person’s BAC may continue to rise up to two hours after their last drink. This means that after your last drink, it could still take a couple of hours for your BAC to reach its peak before it declines.

This is one reason why calculating your BAC and its decline through general rules of thumb like the one above can be unreliable, even though they are generally accepted.

Some websites offer BAC charts that are accompanied by how long it will take for your BAC to reach zero by calculating the number of standard drinks you have consumed and taking into consideration biological factors. These also may not be accurate as unique factors like the type and amount of food consumed before drinking cannot be taken into account.

Using a breathalyser is the easiest and most accurate method to estimate a person’s BAC.

Factors that affect blood alcohol content

Genetics, environment, nutrition, age, and also health factors play a role in a person’s BAC levels after drinking. This means that your mate, who may be older, would likely be intoxicated faster than you due to age-related changes to their bodies. Here are some common factors that affect BAC


Consuming food before or while drinking can slow down the absorption of alcohol into the bloodstream. This can result in a lower peak BAC compared to drinking on an empty stomach. Foods rich in fats and proteins, like cheese and nuts, have a more significant effect in delaying alcohol absorption compared to carbohydrate-rich foods.

Strength of drink

The strength of alcoholic beverages consumed affects your BAC to a significant extent. Drinks with high alcohol content, like full-strength beer or liquor, will lead to a quicker increase in BAC compared to drinks like mid-strength beer or cocktails. Being aware of the alcohol content of your drinks is crucial for understanding how they will impact your BAC. 


Generally, women tend to have a higher percentage of body fat and a lower percentage of water compared to men. Since alcohol is water soluble, the difference in men's and women’s body composition means that females are likely to have a higher BAC after consuming the same amount of alcohol as their male counterparts.


An individual’s emotional state can influence how alcohol affects your body. Drinking alcohol when you feel stressed, anxious or upset can cause the drinks to have a stronger impact on your body. This is because these emotions can affect your body’s stress response and how it metabolises alcohol. 

On another note, alcohol is a depressant which means that it can amplify feelings of sadness or aggression. Be aware of your mental and emotional state before consuming alcohol, as it can affect both your BAC and your drinking experience.


Generally, as you age, your alcohol tolerance level decreases. This means that as you get older, you may feel the effects of alcohol more quickly and in smaller amounts. This is because as you age, your body’s ability to metabolise alcohol gradually decreases. 

Why you need a breathalyser when you drink alcohol

Using a breathalyser when consuming alcohol offers a range of advantages that extends beyond merely estimating your BAC level. Having a breathalyser when you drink reflects a responsible drinker.

Having a breathalyser provides drinkers with enhanced safety and accurate monitoring of BAC levels and can also come in handy when friends and family need to also conduct breath alcohol tests.

READ MORE: Benefits of having a personal breathalyser

Enhanced safety

A breathalyser is a reliable checkpoint you should pass before choosing to drive, go to work or partake in activities that require alertness, coordination and critical thinking. The effects of alcohol on driving tend to be more pronounced as it involves many different cognitive skills. Therefore, if you plan on drinking, do not plan to drive.

Legal compliance

Drink driving penalties in Australia differ by state, but generally, it is a crime punishable by fines and even jail time if an individual is found with a BAC above the legal limit of .05%BAC. Certain workplaces also have drug and alcohol testing policies that will penalise employees that record a BAC reading when on the job.

With this in mind, it’s important to note that your BAC level may not drop to zero even in the morning after drinking. If you have a breathalyser handy, check your BAC before work to make sure you pass the breath test at work.

Care for others

Although having a breathalyser is helpful to drinkers, the reality is that not everyone has their own personal breathalyser. Lending your breathalyser to a mate who thinks that he can drive after drinking could make a stark difference in their journey back home.

Personal monitoring

Having a personal breathalyser is a valuable tool for those that are struggling with alcoholism and are working to beat the addiction. A breathalyser can act as a self-monitoring tool to help individuals pace their drinking and prevent overindulgence and the aftermath linked to it.


How long alcohol stays in your system depends on how long it takes for your BAC level to reach zero once it reaches its peak after consuming alcohol. It can take up to two hours after your last drink for your BAC to reach its peak and an up to another 12 hours for it to reach zero once its peak has been reached.

Genetics, biology, nutrition, age, mood and other factors also play a role in determining how a person metabolises alcohol.

With all of this in mind, it’s clear that estimating a person’s BAC using these rules of measurement is inconvenient and unreliable. Using a breathalyser to estimate your BAC after drinking can help you make more responsible choices and keeps you safe when on the road or even before work.

Some breathalysers, like the AlcoSense Elite 3 BT personal breathalyser, offer a free app to help record BAC readings that can be useful for individuals that are looking to keep track of their alcohol consumption.

Shop Andatech’s wide range of personal breathalysers to help you find the right unit to suit your needs and lifestyle. to help you find the right unit to suit your needs and lifestyle.