Skip to content

How Long Does Alcohol Stay In Your System?

How long does alcohol stay in your system is an important question. It can mean going to jail or keeping a job. Drug testing takes place in the workplace and on the road. A small amount of alcohol can impair judgment and the ability to operate a motor vehicle safely.

  • The legal limit for driving is .08% BAC or above.
  • Receiving a DWI conviction could mean going to prison for years.

Determining blood alcohol content (BAC) depends primarily on the amount of alcohol consumed over the time spent drinking.

Alcohol metabolizes at a rate between .012% to .015% per hour.

Blood Alcohol Content

BAC is the unit of measurement of how much alcohol is in someone’s body (percentage in the blood) at any given moment. BAC is still considered the primary standard for alcohol testing in some labs.

  • BAC is the grams of ethanol in 100 milliliters of blood.

Standard drink

Generally, beer is 4.5% – 5% alcohol for most tests. Wine uses a 5 oz glass, and hard liquor (shots & mixed drinks) uses 1.5 oz at 80 proof.

  • one beer (12 ounces)
  • one glass of wine (5 ounces)
  • 1.5 ounces of liquor (shot)


Use the quick calculator to determine the approximate BAC when a person quits drinking. It also calculates how long it might take for the BAC to go to zero.

How to use

  1. Using the standard drink list above, count the drinks the person had during a continuous drinking episode. Enter it in the top line reading “Number of Drinks Consumed.”
  2. Determine how many hours were spent drinking, and round up to the nearest half-hour. Enter it in the second line reading the “Number of hours Spent Drinking.

Quick BAC Calculator

These results are calculations based on the average rate of human alcohol metabolization. It will be affected by these variables.


The reason gender is a crucial factor is men have a higher percentage (.58) of water weight than women (.49) by almost 10%. That means a woman’s BAC will be slightly higher.

Also, women have a smaller amount of vasopressin or ADH than men.

Absorption rate factors involving gender indicate that a man weighing 140 pounds who consumes two drinks in one hour will have a lower blood alcohol level than a 140-pound woman who drinks the same amount of alcohol in the same amount of time.

It is because men possess higher levels of the enzyme hydrogenase in their stomachs.


How much someone weighs is a factor because BAC is a function of grams of ethanol in 100 milliliters of blood. So, the more someone’s weight, the higher the blood volume in their body.

Other Factors

Other aspects affecting BAC include age, tolerance, and physical fitness. These variabilities could produce a small fraction of error in the final answer. Here is how they might affect the outcome of our formulation.


Younger people have a higher proportion of body water as a fraction of their total weight, and older people have less. So, a younger person may have a lower rate than an older person.

Physical Fitness

Individuals who may be overweight may have a smaller proportion of their body weight than water. Lean people tend to have a more significant fraction of their body weight as water. Therefore, overweight people may have a lower BAC than our formula indicates.


A regular drinker will have a higher ability to metabolize alcohol than someone who does not drink as often.


Most alcohol testing labs now test the body’s chemicals to process alcohol, namely EtG.

This test detects the presence of EtG in the urine. EtG is a direct metabolite the body uses to process alcohol. Its presence detects alcohol consumption in the past 80 hours.

The time factor is dependent on many variables not in this calculation. Therefore, it is merely a rough estimate and not a guarantee of passing a test.


The liver metabolizes most alcohol, with the remainder excreting through urine, sweat, and breath. The human body metabolizes alcohol as soon as the person begins to drink. So, in theory, if you drank at a rate of approximately .015% BAC per hour, your BAC would stay very low.

Once alcohol reaches the stomach, hydrogenase starts breaking down alcohol molecules.

Additionally, alcohol inhibits the production of vasopressin, a hormone that helps conserve body fluids. Without vasopressin to prevent fluid loss, urination increases, and the body usually begins excreting alcohol within 20 to 25 minutes of being consumed.

  • When five percent of absorbed alcohol reaches the kidneys, the body excretes alcohol through urination.
  • Metabolism varies and runs primarily on liver metabolism. Still, it is also related to age, gender, weight, presence of food in the stomach, drinks per hour, percentage of alcohol in the glass, and if the person takes other drugs or medicines.

See how long does meth stay in your system?

more about how tramadol stays in the system