What Is an Alcohol Units Calculator?
An alcohol units calculator works out how many UK alcohol units are in the drinks you consume and compares the total to the weekly guideline set by the UK Chief Medical Officers. You enter the volume of each drink in millilitres and its ABV (alcohol by volume) percentage. The calculator shows your total units for the week, the calorie content, and whether you are within the recommended limit of 14 units.
This is different from a BAC (blood alcohol content) calculator. A BAC calculator estimates how much alcohol is in your bloodstream at a given moment, which changes as your body metabolizes it. An alcohol units calculator measures your total consumption over a week, which is what matters for long-term health risks like cancer, liver disease, and heart disease. If you need to know whether it is safe to drive right now, use our BAC Calculator instead. This tool is for tracking your weekly intake against health guidelines.
What Is an Alcohol Unit?
One UK alcohol unit is 10ml (or 8g) of pure alcohol. That is roughly the amount of alcohol the average adult body can process in about an hour. The concept was introduced in the UK in the 1980s to help people understand how much they were drinking, because alcoholic drinks come in many different strengths and serving sizes. A pint of weak beer and a small glass of wine can contain very different amounts of alcohol even though they look like similar-sized drinks.
The formula is straightforward:
For example, a pint (568ml) of 4% ABV beer contains (568 x 4) / 1000 = 2.27 units. A large glass (250ml) of 14% wine contains (250 x 14) / 1000 = 3.5 units. A single 25ml shot of 40% spirit is (25 x 40) / 1000 = 1.0 unit.
UK Chief Medical Officers' Guidelines
In 2016, the four UK Chief Medical Officers published updated low risk drinking guidelines. The key recommendation, which remains current as of 2026, is:
- To keep health risks from alcohol to a low level, it is safest not to drink more than 14 units per week on a regular basis.
- If you regularly drink as much as 14 units per week, it is best to spread your drinking over 3 or more days. One or two heavy drinking episodes per week increase the risk of death from long-term illness and from accidents and injuries.
- The risk of developing a range of health problems, including cancers of the mouth, throat, and breast, increases the more you drink on a regular basis.
- If you wish to cut down, a good way is to have several drink-free days each week.
- Pregnant women should not drink alcohol at all, as a precaution.
The 14-unit limit applies to both men and women. The previous guidelines, set in 1995, allowed 21 units for men and 14 for women. The change to 14 units for both sexes came after new evidence showed that the cancer risk from alcohol applies at lower intake levels than previously thought, and that the net benefits of small amounts of alcohol are less significant than once believed.
How Many Units Are in Common Drinks?
| Drink | Volume | ABV | Units |
|---|---|---|---|
| Single spirit (gin, vodka, whisky) | 25 ml | 40% | 1.0 |
| Double spirit | 50 ml | 40% | 2.0 |
| Small glass of wine | 125 ml | 12% | 1.5 |
| Standard glass of wine | 175 ml | 13% | 2.3 |
| Large glass of wine | 250 ml | 14% | 3.5 |
| Pint of lower-strength beer | 568 ml | 4% | 2.3 |
| Pint of higher-strength lager | 568 ml | 5.2% | 3.0 |
| Bottle of wine | 750 ml | 13.5% | 10.1 |
Wine has been getting stronger in recent years. Some wines now exceed 14% ABV, and craft beers can reach 6% or more. Always check the label. A large glass of 14% wine at a restaurant is 3.5 units, which is a quarter of the weekly limit in a single drink.
How to Use the Calculator
- Add the drinks you consumed this week. Pick from the common drinks list or add a custom drink.
- For each drink, enter the volume in millilitres and the ABV percentage. Check the label or ask at the bar if you are not sure.
- Set the quantity if you had more than one of the same drink.
- Your total units, calorie estimate, and status appear instantly on the right.
- Check the progress bar to see how close you are to the 14-unit weekly limit.
Example Calculations
Example 1: A Night Out
A 30-year-old man goes to the pub on Friday night and has 3 pints of 4% beer, then shares a bottle of 13.5% wine with a friend (half each, so 375ml).
- 3 pints of beer: 3 x (568 x 4 / 1000) = 3 x 2.27 = 6.8 units
- Half bottle of wine: (375 x 13.5 / 1000) = 5.1 units
- Total: 11.9 units (85% of 14-unit weekly limit in one evening)
- Status: Within weekly limit, but concentrated in one session increases risk
Example 2: A Week of Moderate Drinking
A 45-year-old woman has a medium glass (175ml) of 13% wine with dinner on Tuesday, Thursday, and Saturday, plus one gin and tonic (25ml of 40% gin) on Sunday.
- 3 x wine: 3 x (175 x 13 / 1000) = 3 x 2.28 = 6.8 units
- 1 x gin: (25 x 40 / 1000) = 1.0 unit
- Total: 7.8 units (56% of weekly limit)
- Status: Well within limit, spread over 4 days
Real-World Scenarios
The Wine Glass Size Trap
Karen, a 38-year-old teacher, thought she was drinking moderately. She had one large glass of wine each evening with dinner. When she used this calculator, she discovered that her local pub served 250ml glasses of 14% wine, which is 3.5 units per glass. Over a week, that is 24.5 units, well above the 14-unit limit. She was surprised because she was only having "one glass" each night. She switched to 125ml glasses at home, which reduced her intake to 1.5 units per glass, or 10.5 units per week, bringing her within the guideline.
Cutting Down After a Health Check
James, a 52-year-old accountant, had a routine health check that showed elevated liver enzymes. His GP asked about his drinking. James estimated "a few beers most nights." Using this calculator, he tracked a typical week: 2 pints of 4.5% beer on Monday through Thursday (4 x 2 x 2.56 = 20.5 units) plus a bottle of wine over the weekend (10.1 units). His total was 30.6 units per week, more than double the guideline. He set a target of 14 units by limiting himself to 3 pints on 2 weeknights and sharing one bottle of wine on Saturday. After three months his liver enzymes returned to normal. He also noticed he was sleeping better and had lost 4 pounds, partly because he tracked the extra calories with our Calorie Calculator.
Understanding Craft Beer Strength
Tom, a 26-year-old software developer, started drinking craft IPAs that typically have 6.5% ABV. He usually had 3 bottles (330ml) on a Saturday. Using the calculator, he found that each bottle was (330 x 6.5 / 1000) = 2.15 units, so 3 bottles was 6.4 units. That is 46% of the weekly limit in one sitting. He was not aware that his craft beers contained nearly twice the alcohol of a standard 4% lager. He started alternating with lower-alcohol session beers (3.4% ABV) to reduce his weekly total.
Common Mistakes to Avoid
- Confusing units with drinks: One drink is not one unit. A pint of beer is typically 2 to 3 units. A large glass of wine can be 3.5 units. A bottle of wine is about 10 units. Always calculate based on volume and ABV, not the number of glasses.
- Underestimating wine glass sizes: Pubs and restaurants serve wine in 125ml, 175ml, and 250ml glasses. The large 250ml glass is a third of a bottle and contains 3.5 units at 14% ABV. Many people pour larger glasses at home. Measure with a measuring jug if you are tracking carefully.
- Forgetting that wine is getting stronger: The average ABV of wine has increased over the past two decades. Wines that were 11% in the 1990s are now commonly 13.5% or 14%. A 175ml glass of 14% wine has 2.45 units, compared to 1.93 units for the same glass of 11% wine.
- Binge drinking within the weekly limit: Saving up all 14 units for one or two nights is not low risk. The CMO guidelines explicitly state that spreading drinking over 3 or more days is safer than concentrating it. Heavy drinking sessions increase the risk of accidents, injuries, and acute health problems.
- Assuming beer is always weak: Standard lager is around 4%, but craft beers, IPAs, and stouts can be 6% to 10% ABV or higher. A 330ml bottle of 8% IPA is 2.64 units. Check the label on every bottle or can.
Authoritative Research and Resources
- UK Chief Medical Officers' Low Risk Drinking Guidelines (GOV.UK) - The official UK government publication of the CMO guidelines, including the 14-unit weekly limit, advice on spreading drinking over 3 or more days, and guidance for pregnant women.
- NHS: Alcohol Units - The National Health Service guide to calculating alcohol units, including the formula, examples for common drinks, and the relationship between units and health risks.
- Drinkaware: What Is an Alcohol Unit? - Drinkaware, an independent UK alcohol education charity, provides detailed information on units, standard drinks, ABV, and how to track your intake.