Alcohol Units Calculator
Alcohol units, grams and standard drinks.
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How much alcohol is really in your glass? Enter the drink and how many you've had, and this calculator gives the alcohol units, grams of pure alcohol, and the equivalent US standard drinks — a clear picture for tracking intake.
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Alcohol Units — The Quick Answer
One UK unit is 10 ml of pure alcohol — about half a pint of regular beer, a small glass of wine, or a single spirit measure. Multiply the drink's volume by its ABV to find the units.
Shortcut
Units = (volume in ml × ABV ÷ 100) ÷ 10
Units in common drinks
| Drink | Volume | ABV | Units |
|---|---|---|---|
| Regular beer | 355 ml | 5% | 1.8 |
| Craft beer | 355 ml | 7% | 2.5 |
| Wine | 148 ml | 12% | 1.8 |
| Spirit shot | 44 ml | 40% | 1.8 |
| Large wine | 250 ml | 13% | 3.25 |
US standard drinks work differently: one standard drink is 14 grams of pure alcohol, close to a 355 ml regular beer or a 44 ml spirit shot. This calculator shows both systems.
How It Works
The Formulas
Volume, strength, and units
Formula
Units = (volume ml × ABV/100) ÷ 10 (UK) Grams = volume ml × ABV/100 × 0.789
Variables
Drink volume
How much liquid, in millilitres. A bottle, can, or glass size.
Alcohol by volume
The strength, as a percentage — 5% for regular beer, 12% for wine, 40% for spirits.
Ethanol density
Grams per millilitre, used to convert the volume of pure alcohol to its weight.
Note: Drink-strength labels are the most reliable ABV figure. Home measures are often larger than a standard serving, which quietly raises the unit count.
Worked Example: A 175 ml Glass of 12% Wine
From volume and strength to units
Multiply volume (ml) by ABV %
175 × 12 = 2,100
Divide by 1,000
2,100 ÷ 1,000 = 2.1 UK units
Compare in US terms
≈ 11.8 g alcohol ≈ 0.8 US standard drinks
Reference Guide
| Drink | UK units | US standard drinks |
|---|---|---|
| Regular beer (355 ml, 5%) | 1.8 | 1.0 |
| Small wine (125 ml, 12%) | 1.5 | 0.9 |
| Large wine (250 ml, 13%) | 3.25 | 1.9 |
| Spirit shot (44 ml, 40%) | 1.8 | 1.0 |
What Your Units Actually Mean
Why 'one drink' tells you almost nothing
One UK unit is 10 ml (about 8 g) of pure alcohol; a US standard drink is 14 g, so one US drink is roughly 1.75 UK units. Units let you compare a strong spirit and a weak beer fairly, because both size and strength are built in.
Best for: Comparing very different drinks on equal terms
Free-poured home servings are usually bigger than standard measures, and wine glasses have grown over the years. A generous home glass of strong wine can hold more than two small glasses of lighter wine — which is why people routinely underestimate their intake.
Best for: Getting an honest count of what you actually drink
Any rough BAC figure ignores time, food, sex, medication, and genetics, and must never be used to decide whether to drive — if you've been drinking, don't. If you're concerned about your drinking, speak to a doctor or a dedicated service. This is general information, not medical advice.
Best for: Understanding intake, never judging fitness to drive
What Is a Unit of Alcohol?
A unit of alcohol is a way to express the actual amount of pure alcohol in a drink, so you can compare drinks that look very different. In the UK system one unit is 10 ml (about 8 grams) of pure alcohol; a US 'standard drink' is 14 grams, making one US drink roughly 1.75 UK units. The calculation is simply volume in millilitres times the ABV percentage, divided by 1,000. Because both the size and strength of a drink drive its alcohol content, counting 'drinks' or 'glasses' misleads — a single large glass of strong wine can hold more alcohol than two small glasses of a lighter one. This calculator gives units, grams, and US standard drinks for any drink.
Key Features
💡 Pro Tips
- →Measure your home pours — they're usually larger than a bar's standard measure, which is where hidden units come from.
- →Check the ABV on the label; strong craft beers and wines carry far more units than their 'one drink' appearance suggests.
- →Spread drinks out and alternate with water; the units are the same but the effect on your body is gentler.
- →If you're tracking weekly intake, add every drink's units across the week rather than judging by how many 'drinks' you had.
Common Mistakes
Counting drinks instead of units
'One glass of wine' ranges from about 1.5 to over 3 units depending on size and strength. Only units, which fold in both, give an honest measure.
Underestimating home measures
Free-poured servings and large modern wine glasses hold more than standard measures, so people consistently drink more units than they think.
Using the rough BAC figure to decide about driving
A stationary BAC estimate ignores time, food, body size, and medication. It must never inform a decision to drive — any alcohol means don't drive.
Research & Citations
Sources and standards referenced for the factual claims on this page
- [1]
UK Chief Medical Officers (2016). UK Chief Medical Officers' Low Risk Drinking Guidelines. Department of Health & Social Care.
The UK unit system (10 ml / 8 g of pure alcohol per unit).
View source - [2]
National Institute on Alcohol Abuse and Alcoholism (NIAAA) (2023). What Is A Standard Drink?. NIAAA.nih.gov.
Definition of a US standard drink (14 g of pure alcohol).
View source
This calculator is a reference tool, not a substitute for professional advice. Verify important health, financial, legal, or safety decisions with a suitably qualified professional.
Last updated: October 7, 2026
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Frequently Asked Questions
How many units are in a pint of beer?
A UK pint (568 ml) of 4% beer contains about 2.3 units. The same-pint strength at 5% gives 2.8 units. This calculator uses drink type and volume to work it out exactly.
How many units in a glass of wine?
A small 125 ml glass of 12% wine is about 1.5 units; a medium 175 ml glass about 2.1; a large 250 ml glass about 3. Restaurant pours often lean large, so the units add up quickly.
What is a standard drink?
It varies by country. A US standard drink is 14 grams of pure alcohol (roughly a 355 ml 5% beer). A UK unit is 10 ml — about 8 grams. The calculator shows both so you can compare.
Can I use this to check if I'm safe to drive?
No. The BAC figure here is a very rough stationary estimate that ignores how long you've been drinking, food, sex, medication, and genetics. It must never be used to decide whether to drive — any alcohol means don't drive.