About the Alcohol Content Converter — Grams of Ethanol, US Standard Drinks and UK Units
One drink is not one unit, and a US standard drink is not a UK unit — which is why converting to grams of pure ethanol is the only reliable way to compare intake. The arithmetic is: grams of alcohol = volume in mL × (ABV ÷ 100) × 0.789, where 0.789 g/mL is the density of ethanol. That total then divides by 14 to give US standard drinks, or the pure-ethanol volume divides by 10 mL to give UK units, which works out at roughly 8 g each. A 175 mL glass of 13% wine therefore contains about 18 g of alcohol — 1.3 US standard drinks but 2.3 UK units, the same drink counted almost twice as heavily under one system as the other.
Formula
grams of pure alcohol = volume (mL) × (ABV ÷ 100) × 0.789; US standard drinks = grams ÷ 14; UK units = (volume mL × ABV) ÷ 1000- volume
- Volume of the drink in mL.
- ABV
- Alcohol by volume as a percentage, from the label.
- 0.789
- The density of ethanol in g/mL — the conversion from volume of alcohol to mass.
- 14
- Grams of pure alcohol in one US standard drink.
- ÷ 1000
- Shorthand for dividing the millilitres of pure ethanol by 10; one UK unit is 10 mL of ethanol, about 7.9 g.
- Enter the volume of the drink, not the volume of alcohol in it — this is the commonest input error and it inflates the result roughly tenfold for wine and forty-fold for spirits.
- A UK unit is defined by volume of ethanol (10 mL) while a US standard drink is defined by mass (14 g), which is why UK units and US drinks are not a simple multiple of one another.
- One US standard drink is about 1.75 UK units. Reading a UK unit total as though it were US drinks understates intake by nearly half.
- ABV is volume-based, so the 0.789 density factor is not optional; omitting it overstates grams of alcohol by about 27%.
Interpreting the result
The grams figure is the one to record, because it is the only output that means the same thing everywhere and the only form that maps onto published dose-response data. The bands below express a single occasion's intake against commonly used daily thresholds, and they should be read as an orientation rather than a guideline citation — actual national low-risk limits vary several-fold, so a figure that is 'within limits' in one country may exceed them in another. Two limits of the method itself matter clinically. First, it quantifies one drink, so weekly intake requires multiplying through by frequency, and it is weekly totals rather than single drinks that most guidelines are written around. Second, no quantity of alcohol is a diagnosis: the number informs a conversation about risk and, where indicated, screening with CAGE or AUDIT, which measure dependence and harm rather than volume.
| Score | Band | What it means | Action |
|---|---|---|---|
| ≤ 1 US standard drink (≤ 14 g) | Within typical low-risk daily limits | Within typical low-risk daily limits for most adults | No specific action on volume alone; record the figure and the drinking pattern |
| > 1 to 2 US standard drinks (14–28 g) | Moderate | Approaching or within daily low-risk guidelines, depending on the country | Note that thresholds differ several-fold internationally; check against the guideline your service uses |
| > 2 to 4 US standard drinks (28–56 g) | Above daily limits | Above recommended daily limits in most national guidelines | Counsel on reduction and quantify weekly intake |
| > 4 US standard drinks (> 56 g) | Heavy single occasion | Heavy single-occasion intake | Screen for alcohol use disorder with CAGE or AUDIT; assess for alcohol-related liver disease and withdrawal risk |
Scroll the table sideways for every column.
What the Alcohol Content needs (2 inputs)
- Volume of drink (mL)
- The volume of the drink itself, not the alcohol in it — a 330 mL bottle of beer, a 175 mL glass of wine, a 25 mL spirit measure.
- ABV (%)
- Alcohol by volume, taken from the label. This is a percentage of volume, not of weight, which is why the ethanol density term is needed.
Units. Enter the volume of the drink in mL and the ABV as a percentage from the label. Outputs are grams of pure ethanol (the unit-independent figure), US standard drinks at 14 g each, and UK units at 10 mL of ethanol each. Grams per week is the form most comparable across guidelines and research.
What it returns
- Grams of pure alcohol
- The unit-independent answer, and the one that matches how epidemiological risk data are reported.
- US standard drinks
- Grams divided by 14, the US National Institute on Alcohol Abuse and Alcoholism definition.
- UK units
- Millilitres of pure ethanol divided by 10, giving roughly 8 g per unit.
How it is calculated
This is a unit conversion rather than a derived clinical score, and it is worth being explicit about that: there is no cohort, no regression and no validation study behind the arithmetic, only the density of ethanol and two national definitions. The volume of the drink multiplied by its ABV gives the volume of pure ethanol; multiplying by the density of ethanol, 0.789 g/mL, converts that to mass. From there the two national systems diverge in kind, not just in size. The United States defines a standard drink as a mass — 14 g of pure alcohol — while the United Kingdom defines a unit as a volume, 10 mL of ethanol, which happens to weigh about 7.9 g. That difference in the definitional basis is why the two cannot be reconciled by a single tidy conversion factor and why grams are the sensible common currency.
Facts & figures
| Drink | Volume × ABV | Grams of alcohol | US standard drinks | UK units |
|---|---|---|---|---|
| Spirit measure (UK) | 25 mL × 40% | 7.9 g | 0.6 | 1.0 |
| Bottled beer | 330 mL × 5% | 13.0 g | 0.9 | 1.65 |
| Can of craft beer | 500 mL × 6.5% | 25.6 g | 1.8 | 3.25 |
| Glass of wine | 175 mL × 13% | 18.0 g | 1.3 | 2.3 |
| Large glass of wine | 250 mL × 14.5% | 28.6 g | 2.0 | 3.6 |
| Bottle of wine | 750 mL × 13% | 76.9 g | 5.5 | 9.75 |
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Note how the same drink yields a UK unit figure roughly 1.75 times its US standard-drink figure. A single large glass of strong wine is two US standard drinks.
| Measure | Range found |
|---|---|
| Standard drink size | 8–20 g of pure ethanol (modal value 10 g) |
| Low-risk daily limit, women | 10–42 g |
| Low-risk daily limit, men | 10–56 g |
| Low-risk weekly limit, women | 98–140 g |
| Low-risk weekly limit, men | 150–280 g |
Scroll the table sideways for every column.
Of 75 national governments examined, only 37 were identified as having adopted a standard drink definition at all — which is the strongest argument for recording intake in grams.
How it compares
Alcohol Content vs CAGE questionnaire
This converter measures how much someone drinks; CAGE screens for whether that drinking has become dependent or harmful — quantity and disorder are related but distinct, and neither substitutes for the other.
A patient can drink heavily by volume without meeting criteria for alcohol use disorder, and can screen positive on CAGE at a moderate reported intake. The four CAGE questions probe attempts to cut down, annoyance at others' concern, guilt and morning drinking — behavioural markers that a grams-per-week figure cannot capture. The two are used together: convert the history to quantify exposure and inform liver risk, then screen behaviourally where the pattern or the volume raises concern.
Alcohol Content vs Maddrey's Discriminant Function
Quantifying alcohol intake helps establish that liver disease is alcohol-related; Maddrey's DF then grades the severity of an acute alcohol-related hepatitis once that diagnosis is made.
The two sit at opposite ends of the same pathway. A documented history of heavy, sustained intake is part of what makes alcohol-related hepatitis the working diagnosis in a jaundiced patient, and grams per week is the form in which that history is most defensibly recorded. Maddrey's DF takes over from there, using prothrombin time and bilirubin to decide whether the episode is severe enough to consider corticosteroids. No quantity of alcohol establishes the diagnosis by itself, and no discriminant function value tells you how much the patient drank.
Pearls & pitfalls
- Enter the volume of the drink, not the alcohol within it. A 175 mL glass of wine is 175 mL, not the roughly 23 mL of ethanol it contains.
- A US standard drink (14 g) is about 1.75 UK units (about 8 g each). Treating the two as interchangeable is the error most likely to halve or double a recorded history.
- Wine strength has drifted upward — many wines are now 13 to 15% rather than the 11 to 12% that older unit tables assumed — so historical 'one glass' equivalences understate current intake.
- Home-poured drinks are consistently larger than standard measures, so a self-reported 'glass' or 'measure' should prompt a question about the actual pour.
- This converts a single drink. Weekly intake, which is what most guidelines specify, requires multiplying by frequency — and most guidance is written around weekly rather than single-occasion totals.
- Volume of alcohol and mass of alcohol differ by the 0.789 density factor. Skipping it overstates grams by around 27%.
- The bands here reflect commonly used daily thresholds, not a specific national guideline; actual limits vary several-fold between countries.
Critical actions
- Record intake in grams per week alongside the drink type, volume and ABV, so the figure remains interpretable regardless of which national convention a later reader assumes.
- Ask about the actual pour size for home-poured wine and spirits rather than accepting 'a glass' or 'a measure'.
- Multiply through by frequency to reach a weekly total before comparing against any guideline threshold.
- Screen with CAGE or AUDIT where intake is heavy or the pattern is concerning — volume alone does not identify dependence or harm.
- Assess for alcohol-related liver disease and, where intake is heavy and sustained, for withdrawal risk, rather than treating the converted number as an endpoint.
- State explicitly which system you are using in any documentation that crosses borders, since 'units' and 'drinks' are not equivalent.
Why this score exists
There is no author to credit here, which is itself the point worth making: the standard drink is an administrative convention rather than a scientific finding, and different governments adopted different conventions for reasons of public-health communication rather than pharmacology. The United Kingdom chose a round 10 mL of ethanol because it is easy to compute from a label; the United States chose 14 g because it approximates the alcohol in the country's typical beer, wine and spirit servings. Neither is more correct. The consequence for clinical practice is that the only defensible way to record an alcohol history is in grams per week, with the drink's actual volume and strength documented, because any unit-based figure silently encodes an assumption about which country's convention was used.
About the creator
First author, 37-country comparison of standard drink definitions
Documented that governmental standard drink definitions range from 8 to 20 g of ethanol — the finding that makes converting to grams necessary rather than optional.
Senior author
Co-authored the comparison of national low-risk drinking guidelines that underpins how these figures should be interpreted across borders.
Limitations
- It is a unit conversion, not a validated clinical score — there is no derivation cohort, no performance metric and nothing to validate beyond the arithmetic.
- It quantifies a single drink, so it cannot describe a drinking pattern, and pattern matters independently of volume: the same weekly total spread evenly or concentrated into one session carries different risk.
- The band thresholds reflect commonly used daily limits rather than any single national guideline, and real guidelines differ severalfold between countries.
- It depends entirely on accurate self-report of volume and strength, both of which are systematically under-reported.
- Labelled ABV can differ modestly from actual content, and home-poured measures vary widely from standard servings.
- Grams of alcohol say nothing about individual susceptibility — genetics, sex, body composition, coexisting liver disease and medications all alter the harm a given intake causes.
- No threshold here defines a safe level; large population analyses find risk relationships that begin at low levels of consumption and vary by outcome, age and sex.
If you are the patient
This calculator works out how much pure alcohol is in a drink, using the drink's size and its strength (the ABV percentage on the label). It gives the answer three ways: in grams of alcohol, in US standard drinks, and in UK units. The reason it matters is that these systems do not agree — a UK unit is about 8 g of alcohol while a US standard drink is 14 g, so the same glass of wine can be described as 1.3 drinks or 2.3 units depending on which country's system you use. That is a genuine source of confusion, not a mistake. A 175 mL glass of 13% wine contains about 18 g of alcohol; a 750 mL bottle contains about 77 g. Wine has also become stronger over the years, so older guidance about 'a glass of wine' tends to underestimate what people actually drink now. Grams of alcohol per week is the most useful figure to know, because that is what health guidance and research are based on.
Frequently asked questions
How do you calculate units of alcohol in a drink?#
Multiply the volume in mL by the ABV percentage and divide by 1000 for UK units. For grams of pure alcohol, multiply volume by (ABV ÷ 100) then by 0.789, the density of ethanol. Dividing those grams by 14 gives US standard drinks.
Is a US standard drink the same as a UK unit?#
No. A US standard drink is 14 g of pure alcohol, defined by mass; a UK unit is 10 mL of ethanol, about 7.9 g, defined by volume. One US standard drink is roughly 1.75 UK units, so the two are not interchangeable.
How many units are in a bottle of wine?#
A 750 mL bottle at 13% ABV contains about 77 g of pure alcohol — approximately 9.75 UK units or 5.5 US standard drinks. Stronger wines at 14 to 15% contain proportionally more.
How many grams of alcohol are in a glass of wine?#
A 175 mL glass at 13% ABV contains about 18 g. A 250 mL glass at 14.5% contains about 29 g, which is two US standard drinks in a single glass.
Why does the standard drink size vary between countries?#
Because it is an administrative convention rather than a scientific constant. Across 37 countries with governmental definitions, the modal standard drink was 10 g but the range ran from 8 to 20 g, and low-risk daily limits ranged from 10 to 56 g for men.
Why multiply by 0.789?#
Because ABV is a percentage of volume, and 0.789 g/mL is the density of ethanol — the factor that converts a volume of pure alcohol into its mass. Omitting it overstates the grams of alcohol by about 27%.
Does this calculator tell me if I drink too much?#
It quantifies intake but does not diagnose anything. Low-risk thresholds vary several-fold between countries, and volume alone does not identify dependence or harm — CAGE or AUDIT screening addresses that, and susceptibility to alcohol-related liver injury varies between individuals.
References
Standard drink and guideline definitions
- Kalinowski A, Humphreys K. Governmental standard drink definitions and low-risk alcohol consumption guidelines in 37 countries. Addiction. 2016;111(7):1293-1298.
- National Institute on Alcohol Abuse and Alcoholism. What is a standard drink? (US standard drink = 14 g of pure alcohol).
- UK Chief Medical Officers' low risk drinking guidelines (UK unit = 10 mL of pure ethanol).
Population risk context
- GBD 2016 Alcohol Collaborators. Alcohol use and burden for 195 countries and territories, 1990-2016: a systematic analysis for the Global Burden of Disease Study 2016. Lancet. 2018;392(10152):1015-1035.
- GBD 2020 Alcohol Collaborators. Population-level risks of alcohol consumption by amount, geography, age, sex, and year: a systematic analysis for the Global Burden of Disease Study 2020. Lancet. 2022;400(10347):185-235.