United KingdomTier 1
Alcohol units calculator
Volume and ABV in, UK alcohol units out — 8 g of pure ethanol, 10 mL, is one unit.
Free·No sign-up·Last checked 2026-08-27
Formula
UK units = volume_mL × ABV% ÷ 1000
Grams ethanol = volume_mL × (ABV ÷ 100) × 0.789
Worked example. 25 mL at 40% ABV → (25 × 40) ÷ 1000 = 1 unit, 7.9 g ethanol.
Method
The official NHS/Drinkaware unit formula
This is the simplified formula published by the NHS and Drinkaware, calibrated so that volume in millilitres times the ABV percentage, divided by 1000, gives units directly. It's a close match to dividing grams of ethanol by 8 — the tiny gap comes from the 1000 constant being a rounded, publish-friendly figure rather than the raw ethanol-density calculation.
Questions
8 g of pure ethanol — 10 mL. That's the figure published by the NHS and Drinkaware; other countries define it differently, from 10 g in Australia to 14 g in the US.
A 25 mL single measure of 40% spirit works out to exactly 1.00 unit by design, but a pint of 4.5% lager in the same glass is already about 2.56 units — real drinks vary in both size and strength.
No — this is the ethanol content of the drink as poured, not an absorption or blood alcohol estimate.