About the Alcohol Units Calculator
Most drinking advice is given in "units" or "standard drinks", and most people have only a rough idea how many are in what they actually drink. The rough idea is usually out of date: glasses have grown and wine and beer have got stronger, so the old rule that "a glass of wine is one unit" now undercounts badly.
There is a second problem. A unit is not the same thing everywhere. A UK unit is 8 grams of pure alcohol, an Australian standard drink is 10 grams, and a US standard drink is 14 grams. Advice given in "drinks" in one country is not comparable with another without converting.
This alcohol units calculator works from the one measure that means the same thing everywhere — grams of pure alcohol — and converts it to UK units and to US and Australian standard drinks. It also gives the calories from the alcohol and compares the total with the UK weekly guideline.
How to Use the Alcohol Units Calculator
Pick a drink from the list of common servings, or choose something else and enter the size (in ml or US fl oz) and the strength, shown on the label as ABV or % vol.
Enter how many of that drink. To total an evening or a week of mixed drinks, run the calculator for each type and add the units together.
How Units Are Worked Out
UK units = volume (ml) × ABV (%) ÷ 1000
grams of alcohol = volume (ml) × ABV × 0.789
US standard drinks = grams ÷ 14
Australian drinks = grams ÷ 10
calories from alcohol ≈ grams × 7The UK formula is tidy because a UK unit is defined as 10 ml of pure alcohol, which weighs almost exactly 8 grams (pure ethanol weighs 0.789 g per ml).
Step-by-Step Example
Two 175 ml glasses of 13% wine.
Per glass: 175 × 13 ÷ 1000 = 2.3 units
Two glasses: 2 × 2.3 = 4.5 units
Grams: 350 ml × 0.13 × 0.789 = 35.9 g
US drinks: 35.9 ÷ 14 = 2.6
Calories: 35.9 × 7 ≈ 251 kcalTwo medium glasses of wine is about a third of the UK weekly guideline.
Units in Common Drinks
| Drink | UK units |
|---|---|
| Pint of 4% beer or cider | 2.3 |
| Pint of 5.2% lager | 3.0 |
| 330 ml bottle of 5% beer | 1.7 |
| 125 ml glass of 13% wine | 1.6 |
| 175 ml glass of 13% wine | 2.3 |
| 250 ml glass of 13% wine | 3.3 |
| 750 ml bottle of 13% wine | 9.8 |
| 25 ml single of 40% spirit | 1.0 |
The biggest surprises tend to be the large glass of wine and strong lager, both of which carry far more than people assume.
A Unit Means Different Things in Different Countries
Because each country set its own definition, the same drink counts differently:
UK: 8 g per unit. Guideline: no more than 14 units a week, spread over three or more days.
Australia: 10 g per standard drink. Guideline: no more than 10 standard drinks a week and no more than 4 on any day.
US: 14 g per standard drink. The dietary guidelines advise, for adults who drink, limiting intake to 2 drinks or fewer a day for men and 1 or fewer for women.
Converting everything to grams is the only way to compare them. One US standard drink is 1.75 UK units.
Why the Weekly Guideline Is About Spreading Drinks Out
The UK guideline of 14 units a week is the same for men and women, and it is described as low risk rather than safe. Risk of a range of conditions, including several cancers, rises with any regular drinking.
The guideline also asks for drinks to be spread over three or more days, with several drink-free days. Drinking the same total in one or two heavy sessions carries additional risks — accidents, injuries and acute harm — that averaging over a week hides. Around 6 units or more in a session is commonly treated as a heavy-drinking episode.
Counting at Home
Most undercounting happens at home, where there is no measure.
Wine glasses at home often hold 250 ml or more when filled to a comfortable level — a single large glass can be over 3 units. Pouring into a measuring jug once shows what your usual pour really is.
Spirits poured freehand are commonly two or three times a pub's 25 ml single.
Strength varies by bottle. Craft beers of 6 to 8% and wines of 14 to 15% are common, and the label is the only reliable guide. Checking it once for your usual drinks makes every later estimate better.
Understanding Your Result
Total units is the UK unit count for all the drinks entered.
Per drink gives the units in one serving.
Pure alcohol shows the grams — the common measure behind every system.
In other countries' drinks converts to US and Australian standard drinks.
Calories are those from the alcohol only; mixers and sugar add more.
Against the weekly guideline shows the share of the UK's 14 units.
Worth knowing flags heavy sessions, the size of modern servings, or when no alcohol is advised.
When Should You Use This Calculator?
To check what you actually drink, especially wine by the glass.
When following advice from another country, to convert its "drinks".
When cutting down, to track a week's total accurately.
Not to judge whether it is safe to drive. Units are not a measure of blood alcohol, and the only safe amount before driving is none.
Common Mistakes
Counting a glass of wine as one unit. A 175 ml glass of 13% wine is 2.3.
Assuming all "drinks" are equal. A US drink is 1.75 UK units.
Averaging a heavy weekend over the week. Heavy sessions carry their own risk.
Forgetting home pours. Poured glasses at home are often larger than pub measures.
Ignoring strength. A 5.2% lager has almost a third more alcohol than a 4% beer.
There is no completely safe level of drinking, and no alcohol is the advice in pregnancy and before driving. Nothing here is medical advice.