Alcohol Units Calculator
Units and standard drinks estimate the pure alcohol in a serving; they are not medical advice. Health authorities advise keeping intake low — for example, the UK guideline is no more than 14 units per week. There is no completely risk-free level of drinking.
This Alcohol Units Calculator turns the size and strength of a drink into the amount of pure alcohol it contains, expressed both as UK units and as US standard drinks. One UK unit is 10 ml (about 8 g) of pure ethanol, while a US standard drink holds 14 g. Counting units rather than glasses helps you compare a small strong spirit against a large weak beer on an equal footing.
Formula
UK units = volume(ml) x ABV% / 1000 ; US standard drinks = (volume(ml) x ABV% / 100 x 0.789) / 14
- volume(ml)
- Serving size in millilitres
- ABV%
- Alcohol by volume, as a percentage
- 0.789
- Density of ethanol in grams per millilitre
How it works
- Enter the serving volume in millilitres (or tap a preset like a pint or a wine glass) and set the drink ABV with the strength slider.
- UK units are found directly as volume in ml multiplied by ABV percent, divided by 1000.
- For the US measure the tool computes the pure alcohol in the drink (volume x ABV%, times the 0.789 density of ethanol) and divides those grams by 14 to give standard drinks.
Worked example
A UK pint (568 ml) of 5% ABV beer is converted to units.
- UK units = 568 x 5 / 1000 = 2.84 units.
- Pure alcohol volume = 568 x 0.05 = 28.4 ml, or about 22.4 g.
- US standard drinks = 22.4 g / 14 g per drink, roughly 1.6 drinks.
A pint of 5% beer is about 2.84 UK units, or roughly 1.6 US standard drinks.
Frequently asked questions
- What is the difference between a UK unit and a US standard drink?
- A UK unit is 10 ml (about 8 g) of pure alcohol, while a US standard drink contains 14 g. A US standard drink is therefore roughly 1.75 UK units, which is why the two numbers differ for the same glass.
- How do I find the ABV of my drink?
- ABV (alcohol by volume) is printed on most bottles and cans as a percentage. Typical values are around 4-6% for beer, 11-14% for wine, and 37-45% for spirits like vodka or whisky.
- How many units or drinks are considered low-risk?
- UK guidance is to drink no more than 14 units per week, spread over several days. US guidance suggests up to 1 standard drink a day for women and 2 for men, but health bodies stress there is no fully risk-free level.
- Does this estimate my blood alcohol level?
- No. This tool only counts the alcohol in your drinks; it does not estimate blood alcohol concentration, which also depends on body weight, sex, food, and time. For that, use a dedicated BAC calculator, and never rely on either for decisions about driving.