How to use it
- Enter the Volume of the drink in millilitres, from the label or the glass.
- Enter the Strength as the alcohol by volume on the label, for example 5.2 for 5.2 %.
- Choose Count by: the US definition or the UK unit. Read the first result and the other count below it.
How a standard drink is counted
Each country defines its own standard drink. This page uses two definitions published by national health bodies. In the United States, one standard drink contains about 14 grams of pure alcohol, which the National Institute on Alcohol Abuse and Alcoholism (NIAAA) describes as about 0.6 fluid ounces. In the United Kingdom, one unit is 10 ml of pure alcohol, which the NHS gives as 8 grams.
Pure alcohol is the volume times the strength: a 500 ml drink at 5 % holds 500 × 0.05 = 25 ml of pure alcohol. Grams use the NHS ratio of 8 g to 10 ml, so 25 ml is 20 g. The US count is grams ÷ 14, and the UK count is millilitres ÷ 10.
This is not medical advice. The counts describe the alcohol in a drink, not how it affects you. Ask a doctor or pharmacist about your own drinking, especially if you take medicines or have a health condition.
Pure alcohol (ml) = volume (ml) × strength ÷ 100
Grams = pure alcohol (ml) × 0.8
US standard drinks = grams ÷ 14
UK units = pure alcohol (ml) ÷ 10Standard drinks in common glasses
With this page's counts, each of the three NIAAA examples below comes to about 1.0 US standard drink. The grams come from the NHS ratio, so the figure differs by a few per cent from the NIAAA's 14 g.
- 12 fl oz (about 355 ml) of regular beer at about 5 %: one US standard drink.
- 5 fl oz (about 148 ml) of table wine at about 12 %: one US standard drink.
- 1.5 fl oz (about 44 ml) of spirits at about 40 %: one US standard drink.
- A 568 ml pint of lager at 5.2 %: 2.95 UK units, the NHS's own example.
What this calculator does not include
- The definitions of other countries. This page shows only the US and UK definitions.
- The real measure in a bar or at home, which often differs from the label's volume.
- Food, body weight and how alcohol affects a particular person.
Worked example: a 568 ml pint of lager at 5.2 %
The pure alcohol is 568 × 5.2 ÷ 100 = 29.5 ml. For the UK unit, 29.5 ÷ 10 = 2.95 units, the same figure the NHS gives for this pint.
For the US count the grams come first: 29.536 × 0.8 = 23.6 g, and 23.6 ÷ 14 = 1.69 US standard drinks.
| Measure | Result |
|---|---|
| Pure alcohol | 29.5 ml |
| Grams of alcohol | 23.6 g |
| US standard drinks | 1.69 |
| UK units | 2.95 |
Frequently asked questions
How many units are in a pint of 5% beer?
A 568 ml pint at 5 % holds 2.84 UK units. On the US definition the same pint is about 1.6 standard drinks, because the US standard drink is larger.
Why do the US and UK counts differ?
They use different definitions. The US standard drink holds about 14 grams of pure alcohol, and the UK unit holds 10 ml, which the NHS gives as 8 grams. One US standard drink is therefore about 1.75 UK units (14 ÷ 8).
How much is one unit in the UK?
The NHS defines one unit as 10 ml of pure alcohol, given as 8 grams. A 25 ml measure of spirits at 40 % contains 25 × 0.4 = 10 ml, so it is one unit.
Does this calculator show a safe amount to drink?
No. It counts the alcohol in one drink and does not show a safe limit. Guidance on limits differs between countries, so ask a doctor or pharmacist about your own drinking.
Are the figures I enter sent anywhere?
No. The calculation runs in your browser and nothing you enter is sent to us.
Sources
Figures and text last checked on Thursday, November 12, 2026.