How Long Does Alcohol Stay in Your Body?

Understanding Blood Alcohol Concentration

BAC refers to our blood alcohol concentration. This is the amount of alcohol that’s in your blood. If you have say .06% in your blood it means that you have 60 milligrams per 100 millilitres of blood. Each drink you have will raise the level of alcohol in your blood over time.

When you drink alcohol it moves through your entire bloodstream. The liver breaks down about 90% of the alcohol and the remainder passes out of your body without any change taking place. For one drink this process takes about two hours. If you keep having drinks the alcohol will stay in the liver until it’s processed. The BAC will rise at a rapid rate the more that you drink. Once you stop drinking the BAC will drop but it takes longer to drop than it does to rise.

The weight, sex, height, race and other factors doesn’t factor into how alcohol is metabolised by the body as it’s about the same for everybody. Every hour the alcohol is metabolised at about 0.15. After about 10 hours the person with a BAC of .15 won’t have any alcohol in the bloodstream that can be measured. The mathematical equation for this is .15 divided by .015 = 10.


Under the UK Legal Drink Driving Limit you had a BAC of 0.08 it would take 5.33 hours for all the alcohol to leave your body. With a BAC of 0.08 therefore:

  • 1 hour the BAC would be 0.065
  • 2 hours the BAC would be 0.05
  • 3 hours the BAC would be 0.035
  • 4 hours the BAC would be 0.02
  • 5 hours the BAC would be 0.005

After about 5 hours and 20 minutes the alcohol would be eliminated from your body. Every twenty minutes you metabolise about 0.005 alcohol so the equation is 0.005 x 3 = 0.015

You can tell when your body is going to be free of alcohol but you still need an alcohol tester such as a disposable alcohol test or a breathalyser to know your exact BAC

For a man weighing 10 stone, it’s not difficult to get a BAC of 0.08 as you would need 3 drinks per hour. If you’re binge drinking then the alcohol will stay in the body for over 10 hours.

Testing for Alcohol

 There are three main ways of testing for alcohol. All of these methods can give an approximation of the amount of alcohol in the bloodstream.  If you are self-testing and are concerned that you may be over the limit to drive, one of these alcohol test kits should help you establish your BAC.

Urine Test Kit for Alcohol

Using a urine test for alcohol is a reliable and easy to do. Urine alcohol tests are fairly cheap and produce an indication of BAC in minutes.

Saliva Test Kit for Alcohol

Using a Rapid Saliva Test for Alcohol also produces reliable results and is a less intrusive method of testing if you are screening a young person or employee.  Alcohol Saliva Tests are also fairly cheap to buy and produce reliable results in minutes.

Breath Test Kit for Alcohol

Calculating BAC from breathe can be done by using a breathalyser of disposable Alcohol Breath Test Kit.  The latter tests are a relatively cheap way of testing for alcohol and this type of alcohol screening can be carried out anywhere. A Breath Alcohol Tester often comes in two versions – one detects alcohol at 0.08%, the other detects BAC at 0.02%.

How Alcohol Impacts Your Driving

When you drink, this impacts your ability to drive in a safe manner. As you drink more this only gets worse. Your gender, weight and the amount that you drink, the amount of food you eat, as well as you fast you drink are factors as to how well you’ll operate a vehicle when you’re drinking. Your best bet is to not drink and drive at all no matter how much you have had to drink.

At 0.02 BAC

Some Effects

  • You have some loss of judgement
  • You are relaxed
  • You have a warmer body
  • You have an altered mood

Impact on Driving:

  • You havе impaired functions of your vision such as the ability to track objects quickly
  • You’re ability to do two tasks at the same time is impaired

At 0.05 BAC

Some Effects

  • Your behaviour is exaggerated
  • You may have some loss of your muscle control such as eye focus
  • Your judgement is impaired
  • You will feel good
  • You’re alertness is lowered
  • You have less inhibition

Impact on Driving:

  • You have less coordination
  • You have less ability to track objects
  • You have difficulty with steering
  • You have less response to emergency situations

At 0.08 BAC

Some Effects

  • The muscle coordination is poor. Such as speech, balance, reaction time, hearing, and vision
  • Harder to detect danger
  • Your self-control, reasoning, memory and judgement are impaired

Impact on Driving:

  • You have less coordination
  • You have less ability to track objects
  • You have difficulty with steering

Impact on Driving:

  • Less concentration
  • You have short-term memory loss
  • Less speed control
  • You process information at a slower rate such as signal detection
  • You have impaired perception

At 0.10 BAC

Some Effects

  • Less reaction time or control
  • You have poor concentration, slowed thinking and slurred speech.

Impact on Driving:

  • You have problems breaking and staying in the same lane

At 0.15 BAC

Some Effects

  • You have far less muscle control
  • You may get sick and vomit unless you have a high tolerance for alcohol due to abuse
  • You will have a loss of balance

Impact on Driving:

  • You will have a great deal of difficulty driving a car. Your visual, auditory and other senses will be greatly reduced. You won’t be able to concentrate on the road.

This post has been updated since its original publication in 2013.

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