Alcohol Units Per Week Calculator

What The Weekly Alcohol Units Calculator Does

This calculator estimates UK alcohol units across a typical week. It lets you enter drink size in millilitres, strength as ABV, and how many of that drink you have in the week. It then adds the units, converts them to pure alcohol in grams and millilitres, compares the result with the 14-unit weekly guideline, and shows how the total is spread across drinking days.

The calculator is for awareness and planning, not diagnosis. It cannot decide whether alcohol is safe for you, whether you are dependent, whether you can drive, or whether a medicine interacts with alcohol. The same number of units can carry different risks depending on age, health, pregnancy, medicines, drinking pattern, body size and past alcohol use. If alcohol is causing concern, speak to a GP, pharmacist or local alcohol support service.

The UK Unit Formula

The NHS formula is straightforward: multiply drink volume in millilitres by ABV, then divide by 1,000. A pint of 4.5% beer is 568 x 4.5 / 1,000, which is about 2.6 units. A 175 ml glass of 12.5% wine is 175 x 12.5 / 1,000, or about 2.2 units. A 25 ml measure of 40% spirit is 1 unit.

One UK unit is 10 ml or about 8 g of pure alcohol. The calculator uses that definition for the pure alcohol line. If alcohol calories are shown, it uses 7 kcal per gram of alcohol, so one unit is roughly 56 kcal before mixers, sugar, cream, fruit juice or snacks are added.

Worked Example: Beer, Wine And Spirits

Suppose someone has three pints of 4.5% beer, two 175 ml glasses of 12.5% wine and two 25 ml measures of 40% spirits in a week. The beer contributes about 7.7 units, the wine about 4.4 units and the spirits 2 units. The weekly total is about 14.1 units. That is close to the 14-unit guideline, even though none of the individual drinks looks unusual on its own.

If those drinks are spread over three days, the average on drinking days is about 4.7 units. If most of them are taken on one night, the weekly total is similar but the pattern is different. The calculator therefore asks for drinking days and a peak-day value so the user can see both weekly total and concentration of drinking.

Common Drinks And Units

Important Boundaries

• This page does not calculate blood alcohol concentration or decide fitness to drive.
• Pregnancy advice is different: NHS guidance says the safest approach is not to drink alcohol at all during pregnancy or when planning pregnancy.
• People with liver disease, mental health conditions, medication interactions or past alcohol dependence may need personalised advice.
• If stopping suddenly could cause withdrawal symptoms, seek medical advice before stopping.
• Unit counts are only as good as the drink size and ABV entered.

Practical Ways To Make The Estimate More Accurate

Check labels for ABV rather than using a default strength. Measure a typical home pour once, especially for wine and spirits. Split bottles by the number of people who actually drank them. Count top-ups, doubles, cocktails, fortified wine and strong craft beer separately. If a week is unusual, run a typical week and a higher week so the pattern is visible.