Alcohol and health
Units and standard drinks
How do you work out the units in a cider, and why do UK and US measures differ?
In short
A UK unit is 10 ml — about 8 grams — of pure ethanol, and units are calculated by multiplying the volume in litres by the ABV. A 568 ml pint at 6 per cent is 3.4 units.
A US standard drink is about 14 grams of pure alcohol, roughly 1.75 UK units, so the two systems are not interchangeable and guidance written in one cannot be read as though it were written in the other.
Both are administrative conventions for making different drinks comparable. Neither is a statement that any particular quantity is safe.
The arithmetic
The UK calculation is deliberately simple: units equal the volume in litres multiplied by the ABV expressed as a number. A 500 ml bottle at 4.5 per cent gives 0.5 × 4.5 = 2.25 units. A 2-litre bottle at 7.5 per cent gives 2 × 7.5 = 15 units.
The reason it works out so neatly is that one unit is defined as 10 ml of ethanol, and 1 per cent of a litre is exactly 10 ml. The definition was chosen for that arithmetic convenience.
The US standard drink is defined by mass rather than volume: about 14 grams of pure alcohol, which corresponds to roughly 0.6 fluid ounces of ethanol. In American drink terms it is conventionally illustrated as 12 fluid ounces of 5 per cent beer, 5 fluid ounces of 12 per cent wine, or 1.5 fluid ounces of 40 per cent spirits.
Converting between the two is a matter of dividing: 8 grams against 14 means one US standard drink is about 1.75 UK units, and one UK unit is about 0.57 of a US standard drink. This is why "two drinks" means substantially different things on the two sides of the Atlantic, and why a weekly figure quoted from one country cannot be applied in the other without conversion.
Units in common cider servings
| Serving | ABV | UK units | US standard drinks |
|---|---|---|---|
| 330 ml bottle | 4.5% | 1.5 | 0.8 |
| 440 ml can | 4.5% | 2.0 | 1.1 |
| 500 ml bottle | 4.5% | 2.3 | 1.3 |
| 500 ml bottle | 6.0% | 3.0 | 1.7 |
| Pint (568 ml) | 4.5% | 2.6 | 1.5 |
| Pint (568 ml) | 6.0% | 3.4 | 1.9 |
| Pint (568 ml) | 7.5% | 4.3 | 2.4 |
| Half pint (284 ml) | 7.5% | 2.1 | 1.2 |
| 175 ml glass | 6.0% | 1.1 | 0.6 |
| 750 ml bottle | 5.0% | 3.8 | 2.1 |
| 750 ml bottle | 8.0% | 6.0 | 3.4 |
| 100 ml glass of ice cider | 11.0% | 1.1 | 0.6 |
| 2-litre bottle | 7.5% | 15.0 | 8.6 |
| 3-litre bag-in-box | 6.0% | 18.0 | 10.3 |
What the guidelines say, and what they do not
The UK Chief Medical Officers’ low risk drinking guidelines advise that to keep health risks from alcohol to a low level, both men and women are safest not to exceed 14 units a week on a regular basis; that where 14 units are drunk, they are best spread over three or more days; and that the safest approach in pregnancy is not to drink alcohol at all.
The word "low risk" is doing precise work in that phrasing, and the guidelines are explicit that it does not mean no risk. The World Health Organization states the stronger position directly: no level of alcohol consumption is safe for health.
The US Dietary Guidelines for Americans frame the matter as a limit for those who already drink — no more than two drinks in a day for men and one for women — while stating explicitly that the guidance is not a recommendation to start drinking, and that drinking less is better for health than drinking more.
CiderHQ reports these figures because readers ask what they are. It does not present any of them as a target, an allowance, or an amount that it is advisable to drink.
Where unit counting breaks down for cider
Draught and gravity-dispensed cider is often served without an ABV displayed at the point of service, and traditional cider varies between batches. A unit count based on an assumed strength can be substantially wrong in either direction.
Home-made and farm-gate cider frequently has no declared strength at all, and its actual ABV may be considerably higher than a commercial equivalent. There is no way to count units for a drink whose strength is unknown.
Mulled, mixed and diluted drinks defeat the arithmetic completely, because the volume in the glass no longer corresponds to a known quantity of ethanol.
Where a unit count matters — and it does for driving, for medication, for pregnancy, and for anyone managing their intake — the honest position is that an uncertain strength makes an uncertain count, and an uncertain count should be resolved upwards rather than downwards.
Also answered on this page
Questions this page covers, so you can tell at a glance whether it is the one you want.
- How many units are in a pint of cider?
- What is a standard drink in the US?
- How do you calculate alcohol units?
Related
What people ask next
Questions readers ask about the things this page mentions. Each one goes to the section that answers it rather than to a page written to receive the question.
- How much cider can i drink and still drive — There is no answer to that question that CiderHQ or anyone else can give you. No calculation from units, body weight, time elapsed or how you feel establishes an individual’s blood alcohol concentration, and none of them establishes that you are safe to drive.
- What are the health risks of alcohol, and what does ciderhq say about them — The World Health Organization states that there is no form of alcohol consumption that is risk-free, and its International Agency for Research on Cancer classifies alcoholic beverages, and the ethanol in them, in Group 1 — carcinogenic to humans — the same classification given to asbestos and tobacco.
- What does the body do with alcohol, and why is it’s only cider a mistake at 7.5 per cent — Ethanol is absorbed from the stomach and small intestine into the bloodstream within minutes, and it is eliminated chiefly by liver enzymes at a rate that is roughly constant and cannot be increased at will.
- How accurate is the abv on a cider label — Less accurate than most people assume. UK and EU labelling rules allow ciders and perries a tolerance of one full percentage point either way, so a cider declared at 5.0% may lawfully be anywhere between 4.0% and 6.0%. Still grape wine is held to half that.
Sources
What this page rests on. Where a source is marked as registered rather than read, CiderHQ is recording that the body is authoritative on the subject without claiming to have worked through the document itself. See our evidence policy for what each state means.
NHS · health authority · passage verified 2026-08-24
The definition CiderHQ’s units calculator implements, read against the page rather than assumed: one UK unit is 10 ml or 8 g of pure ethanol, and units are ABV multiplied by volume in millilitres divided by a thousand — which is exactly the arithmetic in `engine/calculators.ts`.
UK Chief Medical Officers’ low risk drinking guidelines
Department of Health and Social Care · health authority · retrieved 2026-08-24
The guidelines that set the UK 14-unit weekly figure, advise spreading consumption over three or more days, and state that the safest approach in pregnancy is not to drink at all. CiderHQ takes its health framing from here rather than from industry material.
Dietary Guidelines for Americans — alcohol
US Departments of Agriculture and Health and Human Services · health authority · registered as competent for this subject
Registered so CiderHQ can state that a US standard drink is 14 g of pure alcohol against the UK unit’s 8 g — a difference that makes cross-country drinking advice non-transferable.
World Health Organization · health authority · passage verified 2026-08-24
The basis for CiderHQ publishing no health benefits for alcohol. Note carefully what this page does and does not carry: it states that no form of alcohol consumption is risk-free and that alcohol is an established carcinogen, but it does not itself set out the IARC classification. That is cited to IARC directly — see `iarc-alcohol-monograph`. The distinction matters because CiderHQ’s own rule is that a source is cited for what it actually says.
International Agency for Research on Cancer, World Health Organization · health authority · passage verified 2026-08-24 · covers Volume 100E, published 2012
Registered separately from the WHO fact sheet because the Group 1 classification is IARC’s and lives in the Monographs rather than on the fact sheet. Several pages here previously attributed it to the fact sheet, which does not carry it. IARC is part of WHO, so the claim was never wrong — it was cited to the wrong document, which is precisely the failure this evidence model exists to catch. The volume was opened on 2026-08-24 and the agent name confirmed: IARC classifies *consumption of alcoholic beverages*, not “alcohol” as a chemical. The distinction is not pedantry — it is the difference between a statement about a behaviour and a statement about a molecule.
A description of what is known, written for readers of legal drinking age. It is not medical advice and it is not an encouragement to drink. CiderHQ publishes no health benefits for alcohol, because current guidance from the major health authorities does not support them. For advice about your own drinking, speak to your national health service. Our policy on alcohol.
Where to go next
- Alcohol and health — The rest of this section, and the position the whole of it is written from.
- Our policy on alcohol — What CiderHQ will and will not publish about drinking, and the reasoning behind it.
- How strong cider is — The strength range cider actually covers, and what drives it.