Alcohol Unit Calculator
Enter the ABV percentage and volume of your drink to get the number of alcohol units it contains, the pure ethanol content in grams, and the calories from alcohol alone. Switch the country to see how the same drink converts under different national standards - unit sizes range from 8 g of ethanol (UK, India) to 20 g (Austria). Preset drink buttons let you fill in a pint, glass of wine, spirit shot, or any other common drink instantly.
Formula
Worked example
A pint (568 ml) of 4.5% ABV lager: ethanol volume = (4.5/100) x 568 = 25.56 ml; ethanol mass = 25.56 x 0.789 = 20.2 g; UK units = 20.2 / 8 = 2.52 units. Calories from alcohol = 20.2 x 7 = 141 kcal.
What is an alcohol unit?
An alcohol unit is a standardised measure of pure ethanol used to help people keep track of how much alcohol they consume. The United Kingdom defines one unit as 8 grams of pure ethanol, which corresponds roughly to a single 25 ml spirit shot at 40% ABV or about half a standard 330 ml can of lager. Different countries use different unit sizes: France, Germany, and Spain define one unit as 10 g, Denmark and Switzerland use 12 g, Portugal uses 14 g, Hungary uses 17 g, and Austria uses 20 g. This means that "one drink" can represent very different amounts of actual ethanol depending on where you live, so when comparing international research or guidelines it is important to check which country standard is being used. The core formula is always the same: alcohol units = (ABV% / 100) x volume in ml x 0.789 (ethanol density) / grams per unit.
How to read your results - units, calories, and weekly limits
The calculator gives you four key numbers. First, the unit count tells you how many standard units the drink (or drinks) contain under your chosen country standard. Second, the pure ethanol figure in grams is the country-neutral measure - useful when comparing beverages across borders. Third, the calorie figure covers the energy from ethanol only (approximately 7 kcal per gram); alcoholic drinks also contain carbohydrates from sugars and fermentable solids, so the real calorie count from a typical beer or wine will be somewhat higher. Fourth, if you enter how many sessions you have per week, the calculator projects your weekly unit total and shows what percentage of the national low-risk guideline that represents. In the UK, the NHS recommends that both men and women keep consumption below 14 units per week, spread over at least three days, with at least two alcohol-free days.
Processing time and blood alcohol
A healthy adult liver metabolises approximately one UK unit (8 g of ethanol) per hour. This rate is fairly constant and cannot be significantly sped up by drinking water, coffee, or food, though food before or during drinking slows absorption into the bloodstream. The processing time shown is therefore a rough lower bound: it assumes a typical adult with no tolerance effects or liver impairment. Body weight, sex, and genetic variation all affect the actual rate. A pint of 4.5% lager (about 2.5 UK units) would take roughly two and a half hours to process, so anyone who has had several drinks should not assume they are below the drink-drive limit the next morning. The UK drink-drive limit is 80 mg of alcohol per 100 ml of blood.
Low-risk drinking guidelines
Low-risk guidelines are not the same as "safe" limits - they represent a level at which the long-term health risk is relatively small for most adults. The UK NHS and Chief Medical Officers advise no more than 14 units per week for both sexes, with those units spread evenly and with two or more alcohol-free days. Ireland HSE guidelines are 11 units for women and 17 for men. France and other European countries use similar frameworks, though the definitions of what constitutes one unit differ, so the absolute ethanol amount can vary. Heavy drinking (more than about 35 units per week for women or 50 for men) is associated with increased risk of liver disease, several cancers, cardiovascular disease, and mental health problems. Binge drinking - typically defined in the UK as more than 6 units in a single session for women or 8 for men - also carries short-term risks regardless of weekly totals.
Alcohol unit definitions by country
| Country | Grams of ethanol per unit | Approx. equivalent |
|---|---|---|
| United Kingdom | 8 g | ~227 ml standard lager (4.5%) |
| Iceland, India | 8 g | ~227 ml standard lager (4.5%) |
| France, Germany, Spain, Ireland, Italy, Netherlands, Poland | 10 g | ~284 ml standard lager (4.5%) |
| Denmark, Finland, Switzerland | 12 g | ~341 ml standard lager (4.5%) |
| Portugal | 14 g | ~398 ml standard lager (4.5%) |
| Hungary | 17 g | ~483 ml standard lager (4.5%) |
| Austria | 20 g | ~568 ml (one UK pint) of standard lager (4.5%) |
One "standard drink" or "unit" is defined differently around the world. The number of grams of pure ethanol per unit is shown below.
Frequently asked questions
How is an alcohol unit calculated?
The formula is: units = (ABV% / 100) x volume in ml x 0.789 (ethanol density in g/ml) / grams per unit. For the UK, one unit = 8 g of ethanol, so a 568 ml pint at 4.5% ABV gives (0.045 x 568 x 0.789) / 8 = 2.52 units. For countries where one unit = 10 g the same pint would be counted as about 2.0 units.
Why do different countries have different unit sizes?
There is no international agreement on what one standard drink contains. National guidelines were set independently over different eras, partly based on population drinking habits and partly on pragmatic serving sizes. The UK chose 8 g when its guidelines were introduced in 1987, while Austria effectively treats a larger pour as the standard. When reading international research you should check which country standard was used, because "one drink per day" means different amounts of ethanol in different studies.
What is the difference between ABV and proof?
ABV (alcohol by volume) is the percentage of the total liquid that is pure ethanol. Proof is an older system still used in the United States, where proof = 2 x ABV. So a spirit labelled 80 proof is 40% ABV. In the UK and most of Europe all labels use ABV. This calculator uses ABV throughout.
Does food affect how quickly I process alcohol?
Food slows the rate at which alcohol is absorbed from the stomach into the bloodstream, which reduces peak blood alcohol concentration, but it does not speed up the liver's metabolism of ethanol. The processing rate of roughly one UK unit per hour applies once the alcohol is in the bloodstream - food just spreads out the absorption phase, so you feel the effects more gradually and peak later.
How many calories are in a glass of wine or a pint of beer?
A 175 ml glass of 12.5% ABV wine contains about 175 x 0.125 x 0.789 x 7 = roughly 121 kcal from ethanol alone. Residual sugars in the wine add another 10-30 kcal depending on whether it is dry or sweet. A 568 ml pint of 4.5% lager yields about 141 kcal from ethanol plus around 100 kcal from carbohydrates, totalling roughly 240 kcal. These are estimates because exact figures vary by brand and fermentation profile.
What is binge drinking?
In the UK, binge drinking is commonly defined as drinking more than 6 units in a single session for women or more than 8 units for men. That is roughly half a bottle of wine or two and a half pints of standard lager in one sitting. The definition varies between countries, but most use a single-session threshold of 4-5 standard drinks in the US (about 56-70 g ethanol). Binge drinking increases short-term risks such as accidents, injuries, alcohol poisoning, and risky behaviour regardless of the weekly total.
Can I sober up faster by drinking coffee or water?
No. Coffee, water, exercise, and cold showers do not increase the rate at which your liver breaks down ethanol. They can reduce some symptoms of intoxication - water prevents dehydration, and coffee temporarily counters drowsiness - but your blood alcohol concentration falls at the same fixed rate regardless. The only thing that lowers it is time.