What this calculator does
A standard drink is a fixed measure of pure alcohol, used so that drinks of different sizes and strengths can be compared on the same scale. It is not the same everywhere: Australia defines a standard drink as 10 grams of pure alcohol, the United States uses 14 grams, the United Kingdom uses 8 grams, and Canada uses roughly 13.45 grams. The same can of beer can be one standard drink in one country and closer to one and a half in another, purely because of where the line is drawn.
This standard drink calculator takes a beverage's volume and alcohol by volume (ABV) percentage, works out the total grams of pure alcohol using the density of ethanol, and divides by the chosen country's standard drink size.
The formula
The calculator multiplies volume by ABV to get the volume of pure alcohol in the drink, then multiplies that by the density of ethanol (about 0.789 grams per millilitre) to convert it to grams. Dividing those grams by the chosen country's standard drink size gives the number of standard drinks.
| Term | Meaning |
|---|---|
| ABV | Alcohol by volume, the percentage of the drink's total volume that is pure alcohol. |
| Pure alcohol content | The weight, in grams, of the ethanol in the drink, independent of any country's standard measure. |
| Standard drink | A country-specific fixed amount of pure alcohol, used as a common unit for comparing different drinks. |
The inputs explained
| Field | What to enter |
|---|---|
| Drink volume (mL) | The volume of the drink, in millilitres, as poured or as stated on the container. |
| Alcohol by volume (%) | The alcohol by volume percentage, usually printed on the label. |
| Standard drink measure | Which country's standard drink definition to divide by. |
When to use it
Comparing a drink against national low-risk drinking guidelines
Most national drinking guidelines are expressed in standard drinks per day or week, so converting an actual drink into that country's standard drinks makes the guideline directly usable.
Working out total standard drinks across an evening
Different drinks, a beer, a glass of wine, a spirit measure, each convert to a different number of standard drinks depending on their volume and strength, even when they feel like similar-sized serves.
Understanding why a drink label from another country reads differently
A bottle labelled as containing a certain number of standard drinks in one country will show a different count if recalculated against another country's definition, purely from the different gram thresholds.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How many standard drinks are in a 355 mL, 5% beer under each country's measure?
The same beer, recalculated against each country's standard drink size.
| Country | Standard drinks | Standard used |
|---|---|---|
| Australia | 1.40 | Australia: 10 g per standard drink |
| United States | 1.00 | United States: 14 g per standard drink |
| United Kingdom | 1.75 | United Kingdom: 8 g per standard drink |
| Canada | 1.04 | Canada: 13.45 g per standard drink |
Questions
Why is a standard drink not the same everywhere?
Each country's health authority sets its own reference amount when writing national drinking guidelines, and there has never been an international agreement to standardise it. The values used here (10 g Australia, 14 g US, 8 g UK, 13.45 g Canada) are the figures each country publishes.
Does a stronger drink always mean more standard drinks?
Not necessarily on its own. A small, strong spirit measure and a large, weaker beer can work out to a similar number of standard drinks, because the calculation depends on the total grams of alcohol, which is volume multiplied by strength, not strength alone.
Is this calculator giving medical advice?
No. It is a unit conversion based on volume, ABV and a published national reference amount. For guidance on what level of drinking is appropriate for you, a doctor or your national health guidelines are the right source, not this or any other calculator.
How accurate is the 0.789 figure used for alcohol density?
It is the standard density of pure ethanol at room temperature and is fixed, it does not vary by drink or country. The main source of imprecision in the result is usually the ABV printed on the label, which is itself an approximation.
To estimate blood alcohol content from a session of drinking, see the blood alcohol content calculator. For a fixed US-only version of this same calculation, see the US standard drinks calculator.