Standard Drink Calculator
Convert a drink's size and ABV into standard drinks.
Results update as you type.
This calculator provides estimates based on population research. Results are not medical advice. Consult a qualified healthcare provider before making health or nutrition decisions.
How it works
Different drinks contain very different amounts of alcohol, and this calculator converts any drink into standard units for easy comparison. You enter the drink's volume in milliliters and its alcohol by volume percentage, and it returns the grams of pure alcohol, the number of US standard drinks, and the number of UK units. The calculation finds the pure alcohol content by multiplying the volume by the ABV fraction and by 0.789, the density of ethanol, which converts the volume of alcohol to grams. It then divides by 14 grams, the US definition of a standard drink, and by 8 grams, the UK definition of a unit. This standardization matters because a small glass of strong spirits can contain as much alcohol as a large glass of beer, and tracking drinks by their true alcohol content is far more meaningful than counting glasses. Health guidelines are expressed in these units: for example, moderate drinking is often defined as up to one or two standard drinks per day, and weekly limits are given in units. Knowing how many standard drinks are in what you actually pour helps you drink within guidelines and understand your intake. Alcohol carries health risks, and less is generally better; this tool is educational, not an endorsement of any level of drinking. Enter the volume and ABV to convert your drink into standard units.
Pure alcohol (g) = volume × ABV% × 0.789 ; US drink = 14 g, UK unit = 8 g
The grams of pure alcohol equal the drink's volume times its alcohol-by-volume fraction times 0.789, the density of ethanol. Dividing by 14 grams gives US standard drinks, and dividing by 8 grams gives UK units, the two common definitions used to standardize alcohol content across different beverages.
Source:NIAAA standard-drink definition
We review all our tools from time to time to ensure accuracy.
Worked example
How to use this calculator
- 1
Enter your values
Enter drink volume and alcohol by volume (abv).
- 2
Adjust the options
Fine-tune any options to match your situation.
- 3
Read your result
US standard drinks updates instantly as you type — no button to press.
Frequently asked questions
What is a standard drink?
A standard drink is a fixed amount of pure alcohol used to compare beverages. In the US it is 14 grams of pure alcohol, roughly a 355 mL beer at 5%, a 150 mL glass of wine at 12%, or a 44 mL shot of spirits at 40%. The UK uses a smaller unit of 8 grams. Standard measures make it easier to track intake against guidelines.
How is pure alcohol content calculated?
Multiply the drink's volume by its alcohol-by-volume fraction to get the volume of alcohol, then multiply by 0.789, the density of ethanol, to convert to grams. For example, 355 mL at 5% is about 17.8 mL of alcohol, which weighs roughly 14 grams. Dividing by the standard-drink size gives the number of standard drinks or units.
Why do US and UK measures differ?
The two systems simply chose different reference amounts. A US standard drink contains 14 grams of pure alcohol, while a UK unit contains 8 grams, a little over half as much. So the same beverage equals more UK units than US standard drinks. The calculator shows both so you can apply whichever guideline is relevant to you.
How does ABV affect the number of drinks?
ABV, alcohol by volume, is the percentage of a drink that is pure alcohol, so higher ABV means more alcohol in the same volume. A craft beer at 8% contains far more alcohol than a light beer at 4% of the same size. That is why counting glasses can mislead, and converting by volume and ABV gives the true standard-drink count.
What are the drinking guidelines?
Guidelines vary by country, but many define moderate drinking as up to one standard drink a day for women and up to two for men, with recommended weekly limits. Health authorities increasingly emphasize that less alcohol is better and no level is completely risk-free. This calculator helps you measure intake accurately; it does not recommend any particular amount.