Knowing how many units of alcohol are in your drinks helps you stay within lower-risk guidelines and understand your intake. The Alcohol Units Calculator converts any drink into UK units and US standard drinks from its volume and alcohol-by-volume (ABV), with presets for common beers, wines and spirits.
How it works
The UK unit is based on pure alcohol: one unit is 10 ml (about 8 g) of ethanol. The core formula is:
UK units = volume (ml) × ABV (%) ÷ 1000
For the US measure, a standard drink contains 14 g of pure alcohol. The tool converts millilitres of ethanol to grams using ethanol’s density of 0.789 g/ml, so one UK unit (about 7.9 g) equals roughly 0.56 US standard drinks. Multiply by the number of drinks for your session total.
Example
A 568 ml pint of 4% ABV beer:
568 × 4 ÷ 1000 = 2.3 UK units (about 1.3 US standard drinks).
| Drink | Volume | ABV | UK units |
|---|---|---|---|
| Pint of beer | 568 ml | 4% | 2.3 |
| Glass of wine | 175 ml | 13% | 2.3 |
| Single spirit | 25 ml | 40% | 1.0 |
UK Chief Medical Officers advise no more than 14 units a week, spread over three or more days. Everything runs in your browser — nothing is uploaded.
Comparing UK units to US standard drinks
The two systems use different definitions of a “drink,” which causes confusion when reading cross-national health guidelines:
| Measure | Pure alcohol |
|---|---|
| 1 UK unit | ~8 g (10 ml of ethanol) |
| 1 US standard drink | 14 g |
| 1 WHO drink | ~10 g |
A UK pint of 4% beer (2.3 units) equals roughly 1.3 US standard drinks. This matters because US guidelines reference standard drinks while UK guidelines reference units — the underlying advice is similar, but the numbers look different.
ABV variation by drink type
ABV varies more than many people realise:
| Drink | Typical ABV range |
|---|---|
| Session beer / lager | 3.5%–4.5% |
| Craft IPA | 5.5%–8% |
| Standard wine | 11%–13.5% |
| Fortified wine (port, sherry) | 17%–20% |
| Spirits (whisky, gin, vodka) | 37.5%–43% |
| Alcopops | 4%–5% |
A pint of strong craft IPA at 7% carries nearly twice the units of a session beer: 568 × 7 ÷ 1000 = 4.0 units — almost a third of the weekly guideline in a single pint.
Practical counting tips
- Use the label. ABV is printed on every bottle, can, and pump clip in the UK. The formula (volume in ml × ABV% ÷ 1000) works directly from those figures.
- Track the session, not just the drink. A single gin and tonic with a 50 ml double is 2 units; four of them is 8 — more than half the weekly guideline in one evening.
- Large wine glasses mislead. A restaurant 250 ml pour of 13% wine is 3.25 units, not the “one glass” many people mentally assign to it.
- Drink-free days reduce harm. The Chief Medical Officers’ guidance specifically recommends spreading consumption across three or more days and having several alcohol-free days each week, even within the 14-unit limit.
When this tool is most useful
This calculator is helpful for anyone wanting to track weekly intake against the 14-unit guideline, for healthcare professionals helping patients assess consumption, and for anyone comparing the unit cost of drinking at home versus in a pub. It does not assess dependency or health risk — for that, use a validated screening tool or speak with a GP.