For the Family & Loved Ones

Alcohol By Volume (ABV) and “Proof” Explained

This article originally appeared on: and was written by Lisa Frederiksen

Alcohol By Volume (ABV) can be very difficult to determine. (Another term you often hear related to ABV is “proof.”) But it’s an important concept to understand in order to stay in control of one’s drinking, which is why I have updated my 2011 post on this topic.

I’m updating this post because one of the most common reasons people find themselves inadvertently drinking more than they’d intended is the confusion that surrounds the idea of “A” (one) drink. Another reason is the confusion about how much alcohol is in a particular type of alcoholic beverage (in other words, the alcohol by volume). When a person drinks too much – loses control of their drinking – they increase the likelihood of their causing harm to themselves and others.

Before you continue reading, it is important to know that one standard drink is defined as: 5 ounces of table wine, 12 ounces of beer, 1.5 ounces of distilled spirits (e.g., vodka, whiskey), 8-9 ounces of malt liquors or 3.3 ounces of champagne.

Alcohol By Volume (ABV) and “Proof” Explained

As you probably know, alcohol is one of the ingredients in beverages with names like beer, wine, tequila, and champagne. Alcohol is the ingredient that gets you drunk.  But it is not something that grows on a tree or in the ground. It is something that is created by a process called fermentation.

The scientific term for alcohol is ethanol or ethyl alcohol. To get ethanol (alcohol), people mix yeast (you may know of yeast because it is used in baking) and sugar – the kind of sugar that is naturally found in fruits and vegetables.

When mixed together over time, the yeast breaks down the sugar into ethanol and carbon dioxide. This process is called fermentation. As the fermentation process continues, the carbon dioxide gas bubbles out, and all that is left is the ethanol and water.

Different sugar sources make different kinds of alcohol. The sugar from crushed grapes, for example, is used to make wine. The sugars from grain, potatoes, beets and other plants are used to make vodka.

Alcoholic beverages like vodka, rum, gin, and whiskey go through another process called distilling. Distilling is the process that removes the water from the ethanol. This is why you hear of vodka, rum, gin, whiskey and the like being called, “distilled spirits.”

So what are you supposed to do with this information?

If you look at a label on a bottle of wine, you will see – usually in very tiny letters – something like ABV 14% or ALC. BY VOL. 14%. This is saying that in that particular bottle, 14% of the liquid is alcohol. In other words, the alcohol by volume (ABV) is 14%.

Distilled spirits are labeled differently. If you look on a bottle of distilled spirits, you will see another number and word – also in very tiny letters – that will read “80- proof.” Proof is a number equal to twice the ABV. So in a bottle of 80-proof vodka, for example, the ABV (alcohol by volume) is 40%, which explains why you would get drunk on 10 ounces of vodka but maybe not get drunk on 10 ounces of wine. In other words, both are 10 ounces, but the vodka contains a lot more alcohol by volume than does the wine (40% vs 14%). This also explains why a 1.5 ounce shot of 80-proof vodka and 5 ounces of wine are both equal to “A” (one) drink. Though very different in size (1.5 ounces vs 5 ounces), each one contains the same amount of ethyl alcohol, therefore both are considered to be a standard drink.

What’s missing from these kinds of labels is the kind of information that puts the ABV percentage in context of how much ethyl alcohol is in a drink and how many drinks are in a container.

Where’s the standard drink label when you need It?

So, the question still remains, “How does ABV or proof tell a person how much alcohol is in “A” (one) drink?” Answer: It doesn’t.

This is where having a standard drink label that informs you of how many drinks are in a particular cocktail or in particular can or bottle would really help. Take a bottle of table wine, for example. A standard drink label would tell you how many “drinks” (standard drinks) of wine there are in that particular bottle. The label could be very simple. It could be something along the lines of: SD = 5. [SD = standard drinks.]

Since there is no such thing as a standard drink label, the next best thing is to take a look at the picture above and realize that each glass contains “A” drink. In other words, one standard drink or the same amount of ethyl alcohol as in the drink before and the drink after shown in this picture.

Then browse through the National Institute on Alcohol Abuse and Alcoholism (NIAAA)’s website, Rethinking Drinking. There you will find two online calculators that will help you determine the amount of ethanol (ethyl alcohol) – in other words, the alcohol by volume – in various types of alcoholic beverages and containers. One is the Drink Size Calculator and the other is the Cocktail Content Calculator.

Why is understanding alcohol by volume and standard drinks so important?

Because it’s the ethyl alcohol chemicals in alcoholic beverages that change the way a person’s brain works. These brain changes, in turn, change a person’s thoughts, feelings, and behaviors, and can result in their exhibiting drinking behaviors.

Drinking behaviors include: verbal, physical, emotional abuse; neglect; blackouts; unplanned/unwanted sex; breaking promises to stop or cut down; shaming, blaming, denying; unpredictable behaviors; and driving while impaired, to name a few.

So, why does ethyl alcohol (ethanol) change the way the brain works and potentially cause a person to exhibit drinking behaviors? The answer has to do with how the body processes alcohol.

Understanding How the Body Processes Alcohol (Ethyl Alcohol)

Alcohol is not processed like other foods and liquids through the digestive system. Instead it passes through the stomach and enters the bloodstream through the walls of the small intestine. Because alcohol dissolves in water, the bloodstream carries it throughout the body, which is 60-70% water, where it is absorbed into body tissue and organs high in water concentration and highly vascularized (meaning lots of blood vessels). One such organ is the brain.

The ethyl alcohol chemicals in alcoholic beverages can only leave the body by what happens in the liver. Enzymes produced only in the liver, called ADH and ALDH, break down (metabolize) the ethyl alcohol chemicals so they can leave the body. These liver enzymes can only metabolize a certain amount of ethyl alcohol per hour, which means alcohol leaves the bloodstream more slowly than it enters. This rate of metabolism explains why a person’s Blood Alcohol Content (BAC) can continue to rise long after that individual has stopped drinking or passed out.

Contrary to popular belief, then, we cannot rid our bodies of the ethyl alcohol chemicals in the alcoholic beverages we drink by peeing, sweating, or vomiting. Similarly, drinking coffee or lots of water or eating a big meal or taking a walk around the block will not get rid of these chemicals, either. The only thing that can sober a person up is TIME.

As a very GENERAL rule of thumb, it takes about one hour for the liver to metabolize the ethyl alcohol chemicals in one standard drink. And recall a standard drink is defined as 5 ounces of table wine, 12 ounces of regular beer, and 1.5 ounces of hard liquor. Using this very GENERAL rule of thumb, it will take four hours to metabolize four standard drinks – even if the drinks were consumed back-to-back in a short period of time.

When a person drinks more than their liver can metabolize, the excess ethyl alcohol chemicals “sit” in body organs high in water concentration and highly vascularized – like the brain. While waiting their turn out the liver, these ethyl alcohol chemicals interrupt the brain’s normal cell-to-cell communication process. These changes, in turn, are what cause a person to engage in drinking behaviors, such as: saying mean things, getting into a fist fight, or thinking that having unprotected sex is a good idea.

Or a person may “choose” to drink and drive because they “feel fine.” And it’s likely true. At the point they gather their keys and head out, they may be “fine.” But as the ethyl alcohol chemicals back up (blood alcohol content continues to rise), these chemicals interrupt normal brain functioning. This causes the person to slur their words, not think about the speed limit, not be as quick with their braking reflexes, and find their vision is blurred.

Keeping the general rule of thumb of one hour per one standard drink in mind, you can judge how compromised you or someone else is based on how much they’ve had to drink. But before I leave this topic, there’s a wrinkle in the simplicity of all of this that I need to explain, and it’s the variables.

Variables That Change How a Person Handles Alcohol

No two people will necessarily metabolize alcohol in the same manner. People who weigh less, for example, have less body water as compared to someone who weighs more, and thus drink for drink a person who weighs less will have more alcohol concentration in their body water than someone who weighs more. People who have lower amounts of the liver enzymes that metabolize ethyl alcohol will take longer to metabolize the same amount as someone else. Stage of brain development also has an influence. There are other variables, as well, such as taking medications, lack of sleep, stress, or existence of a mental illness, that can also influence how much is “too much” for one person as compared to another or for the same person from one drinking episode to the next.

Staying in Control

The NIAAA gives healthy adults a target for staying within “low-risk” drinking limits, which is how a person avoids the consequences of too much ethyl alcohol in their brain and body:

  • Men:         More than 4 drinks on any day or 14 per week
  • Women:   More than 3 drinks on any day or 7 per week

For information on “excessive” drinking, check out these links provided by the Centers for Disease Control (CDCC): binge drinkingheavy drinkingany alcohol use by people under the age 21 minimum legal drinking age, and any alcohol use by pregnant women.

To learn more about you own or someone else’s drinking, visit NIAAA’s Rethinking Drinking > How Much is Too Much.