Alcohol units and standard drinks both describe pure alcohol, but they use different amounts. Knowing which system your local guidance uses prevents a small-looking conversion error from becoming a large weekly mismatch.
The UK alcohol unit formula
One UK unit equals 10 millilitres or 8 grams of pure alcohol. To calculate units, multiply the drink volume in millilitres by its ABV, then divide by 1,000. A 500 ml beer at 5% ABV is 2.5 UK units: 500 × 5 ÷ 1,000.
The NHS advises people who drink regularly not to exceed 14 units a week and to spread intake across three or more days. Guidance is not a target, and drinking less reduces risk.
The US standard drink formula
One US standard drink contains about 14 grams or 0.6 fluid ounces of pure alcohol. Common examples are 12 ounces of 5% beer, 5 ounces of 12% wine, or 1.5 ounces of 40% spirits.
A 16-ounce craft beer at 8% is not one standard drink. Its higher strength and larger volume make it roughly two standard drinks, which is why logging container size and ABV matters.
Why the same drink gets two numbers
Because a UK unit contains 8 grams and a US standard drink contains 14 grams, one US standard drink is about 1.75 UK units. Both systems can be accurate; the important part is to use one consistently and compare it with guidance written for that system.
- 330 ml beer at 5%: about 1.65 UK units
- 175 ml wine at 12%: about 2.1 UK units
- 25 ml spirit at 40%: 1 UK unit
- US examples use ounces and a 14-gram standard drink
Let the tracker preserve the original inputs
Conversions are most useful when you can still see the serving and ABV behind them. Alcohol Tracker° records the drink, calculates comparable units, and keeps daily and weekly totals together. That makes it easier to correct an entry and understand why a stronger beverage changed the total.
Sources
Reviewed against current public-health guidance:
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These related guides add context to the terms and measurements discussed above:
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