Alcohol is measured in different ways in different countries, and the phrase a couple of drinks does not tell you how much you actually consumed. This alcohol units calculator converts a drink size and strength into standard units, estimates your blood alcohol concentration from your weight, and shows the calories involved so you can see what an evening adds up to.
What Is the Alcohol Units Calculator?
A unit is a simple way to compare drinks of very different strengths and sizes. In the United Kingdom one unit is 10 millilitres of pure alcohol, which is roughly a quarter pint of ordinary lager, a small glass of wine or a shot of spirit.
This calculator converts any drink into units, which is the only fair way to compare a pint of lager with a large glass of wine, and then estimates the concentration of alcohol in your blood so you can see how the number relates to the legal limits.
How the Units and Blood Alcohol Estimate Work
Units = volume in ml × strength as a fraction ÷ 10
A 175 millilitre glass of wine at 12 percent gives 175 times 0.12 divided by 10, which is 2.1 units. A 568 millilitre pint of lager at 4.5 percent gives 2.56 units, so the pint is slightly more than the glass.
The blood alcohol estimate uses the Widmark relationship, dividing the mass of alcohol consumed by the total body water, which is taken as 68 percent of body weight for men and 55 percent for women. The figure falls by roughly 5 percent per hour as the liver metabolises alcohol.
Why Units Are More Useful Than Drinks
A single large glass of wine contains more than twice the alcohol of a small one, and a double spirit contains roughly three times a single. Counting drinks hides that variation completely.
Units also make weekly guidance easy to apply. Most UK health guidance treats 14 units a week as a low risk limit, and roughly two thirds of people in the country drink more than that. Two 175 millilitre glasses of wine is 4.2 units, so three of those is already half the weekly guidance in one sitting.
Limits and Safety
The blood alcohol estimate is a rough approximation that assumes alcohol is absorbed quickly, is evenly distributed and that metabolism follows the average rate. Food, drink type, individual variation and liver health all change the real figure, and some people clear alcohol considerably faster than others.
Never use this estimate to decide whether to drive. If there is any doubt, do not drive, and remember that alcohol is still being processed the following morning.
Frequently Asked Questions
How many units are in a large glass of wine?
A 175 millilitre glass of wine at 12 percent ABV contains 2.1 units. At 14 percent it is 2.45 units, and a 250 millilitre glass of the same wine is 3 units.
What is the recommended weekly limit?
UK guidance treats 14 units a week as a low risk limit and advises spreading that across several days rather than saving it for one occasion. Some countries use different units and different thresholds, so check the guidance that applies where you live.
How long does it take to sober up?
The liver removes alcohol at a fairly constant rate of roughly 8 to 10 grams per hour for most people, so sobering up takes time rather than effort. A large night out can take well over 12 hours to clear completely.
Why do women get a higher blood alcohol reading?
On average women have a higher proportion of body water than men, so the same amount of alcohol is diluted in less fluid and the concentration in the blood is higher. The Widmark equation accounts for this with different body water constants.
Does food stop you getting drunk?
Food slows the absorption of alcohol, so the peak concentration is lower and arrives later, but the total amount of alcohol consumed does not change. It makes the difference between a slower rise and a less severe one, not a safe drink.