Alcohol Units per Week Calculator
Convert your typical drinks into UK alcohol units per week, grams of pure alcohol and US standard drinks, and compare with the 14-unit guideline.
How it works
Units per drink = volume(ml) × ABV% ÷ 1000 · weekly units = units/drink × drinks · grams = units × 8 · US standard drinks = grams ÷ 14
One UK alcohol unit is 10 ml (about 8 g) of pure ethanol, and any drink’s units equal its volume in millilitres times its ABV percentage, divided by 1,000. Adding up a week of drinking lets you compare against the UK Chief Medical Officers’ low-risk guideline of no more than 14 units per week for both men and women, ideally spread over three or more days. The same ethanol total also converts to US standard drinks, which are defined as 14 g each.
Worked example
A 175 ml glass of 13% wine is 175 × 13 ÷ 1000 = 2.3 units. Ten such glasses a week is 22.8 units — about 182 g of pure alcohol, roughly 13 US standard drinks, and 8.8 units over the 14-unit guideline.
Sources: UK CMO low-risk drinking guidelines
Frequently asked questions
How many units is a "safe" amount?
UK guidance says keeping below 14 units a week keeps health risks low, with no completely safe level. Spreading those units across several days and having drink-free days is advised rather than concentrating them.
How is a UK unit different from a US standard drink?
A UK unit is 8 g of pure alcohol; a US standard drink is 14 g — about 1.75 UK units. This calculator reports both so you can use whichever your guidance uses.
Why does a large glass of wine count as more than one drink?
A 250 ml glass of 13% wine is about 3.25 units — over three times a single unit — because both the larger volume and the higher strength raise the ethanol content. Bigger, stronger servings add up fast.
Related calculators
Educational estimate only — not medical advice. Individual needs vary; consult a qualified professional before making health decisions.