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Standard Drink Calculator

Count the standard drinks or alcohol units in a drink from its volume and ABV. Use US, UK, Australian or custom definitions.

Level: Grades 6–7

  • Common Core standard 6.RP.A.3.cFind a percent of a quantity as a rate per 100 (e.g., 30% of a quantity means 30/100 times the quantity); solve problems involving finding the whole, given a part and the percent.
  • Common Core standard 6.RP.A.3.dUse ratio reasoning to convert measurement units; manipulate and transform units appropriately when multiplying or dividing quantities.
Printable worksheet

Standard Drink Calculator

Know the answer you need? Pick an input to work backward.

Inputs

Printed on the label, for example 5% for many beers, 12–14% for wine, 40% for many spirits.

Result

Number of US standard drinks

1

This drink contains about 14 g of pure alcohol, or 1 US standard drinks. This tool does not estimate blood alcohol or impairment.

Pure alcohol (mass)
14 g
Pure alcohol (volume)
17.7 mL

See the step-by-step solution ↓

Step-by-step solution

  1. Convert the volume to milliliters (1 US fl oz = 29.57353 mL exactly)

    12 US fl oz×29.57353=354.88 mL

  2. Multiply by the ABV, the share of the drink that is alcohol, to find the volume of pure alcohol

    354.88 mL×5%100=17.744 mL

  3. Multiply by the density of ethanol (0.789 g/mL) to get its weight in grams, since standard drinks are defined in grams

    17.744 mL×0.789=14 g

  4. Divide by the grams of alcohol in one standard drink (14 g)

    14 g14 g=1

Test yourself

20 quick questions built from this calculator's formula: work out results, predict what happens when an input changes, and work backward from an answer. Every answer comes with the working.

Please note: This calculator gives a general screening estimate, not a diagnosis. Talk to a qualified healthcare professional about your individual health.

What this calculator does

Find out how many standard drinks are in what you pour. A "standard drink" is a fixed amount of pure alcohol. It lets you compare drinks of different sizes and strengths. A small glass of strong wine and a large can of light beer can hold the same amount of alcohol. Counting in standard drinks shows that at a glance. Health guidance on alcohol is usually written in these terms. So knowing how many standard drinks are in your glass is the first step to comparing your drinking with that guidance.

The catch is that the definition varies by country. A US standard drink is 14 grams of pure alcohol. A UK unit is 8 grams (10 mL), and an Australian standard drink is 10 grams. This calculator lets you choose the definition, or enter your own. It works out the alcohol from the volume and the ABV printed on the label. It does not estimate blood alcohol concentration, impairment or whether it's safe to drive. Those depend on many personal factors that a calculator like this can't know. No one should rely on a number to decide whether they're fit to drive.

Where it's used

Why this math matters outside the classroom:

  • Grams of alcohol. A 355 mL drink at 5% ABV holds 355 × 0.05 × 0.789, about 14 g of alcohol, which is one US standard drink.
  • Wine pours. A 150 mL glass of 13% wine holds about 15.4 g of alcohol, slightly more than one US standard drink.
  • Reading labels. Comparing a 12 oz can at 8% ABV with one at 4% shows the stronger can counts as twice as many standard drinks.
  • Country definitions. The same 14 g of alcohol is 1 US standard drink, 1.75 UK units and 1.4 Australian standard drinks.
  • Party planning. Hosts count the standard drinks in a punch recipe from its total volume and strength before serving it.

Grade level and standards: Grades 6–7; Common Core State Standards for Mathematics 6.RP.A.3.c, 6.RP.A.3.d. © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.

How to use it

  1. Enter the volume of one drink and choose its unit (milliliters, liters, US or imperial fluid ounces, or pints).
  2. Enter the ABV (alcohol by volume) from the label.
  3. If you had several of the same drink, enter how many.
  4. Choose the standard drink definition for your country. Or pick custom and enter the grams per drink.

What the inputs mean

Drink volume
Measure what's actually poured. Restaurant and home pours of wine and spirits are often larger than the stated serving size.
Alcohol by volume (ABV)
Alcohol by volume, as a percentage. It's printed on almost all alcoholic drinks. For a home brew, the ABV calculator can estimate it from gravity (sugar) readings.
Standard drink definition
Other countries use other definitions, from around 8 g to 20 g. Choose custom and enter the grams if your country's guidance uses a different figure.

Formula and method

Pure alcohol (mL) = volume (mL) × ABV ÷ 100
Pure alcohol (g) = pure alcohol (mL) × 0.789 g/mL
Standard drinks = pure alcohol (g) × number of drinks ÷ grams per standard drink

ABV tells you what share of the drink's volume is ethanol (drinking alcohol). So multiplying the volume by ABV gives the volume of pure alcohol. Standard drinks are defined by weight, so that volume is multiplied by the density of ethanol. That's about 0.789 grams per milliliter at room temperature. Volumes in other units are first converted to milliliters using exact factors (1 US fl oz = 29.5735295625 mL; 1 imperial fl oz = 28.4130625 mL).

The UK unit is officially defined as 10 mL of pure alcohol, which at 0.789 g/mL is 7.89 g. It's also commonly stated as 8 g. This calculator uses 8 g. So its UK unit counts come out about 1.4% lower than the volume-based rule of ABV × volume in liters.

Worked example

How many US standard drinks are in a 12 fl oz can of beer at 5% ABV?

  1. Volume in mL: 12 × 29.5735295625 = 354.88 mL.
  2. Pure alcohol: 354.88 × 5 ÷ 100 = 17.744 mL.
  3. Mass of alcohol: 17.744 × 0.789 = 14.000 g.
  4. Standard drinks: 14.000 ÷ 14 = 1.00.

Result: A 12 fl oz can of 5% beer contains 14.0 g of alcohol, which is 1.00 US standard drink.

Understanding the result

The result tells you the amount of alcohol in a drink, in the units your local guidance uses. It measures what's in the glass, not its effect on you.

Many common servings are more than one standard drink. A large glass of wine or a double measure of spirits can easily be two or more. Strong craft beers in large cans can be close to three US standard drinks.

If you're trying to keep track of how much you drink, counting standard drinks over a week tells you more than counting glasses. For personal advice about alcohol, talk to a healthcare professional.

Assumptions and limitations

  • The ABV on the label is accurate.
  • Ethanol density is taken as 0.789 g/mL. The exact figure changes slightly with temperature.
  • Each of the drinks counted has the same volume and ABV.
  • It does not estimate blood alcohol concentration, intoxication, impairment or fitness to drive. It should never be used for those purposes.
  • It does not give drinking limits or advice. Guidance differs by country and by person.
  • For mixed drinks, work out each alcoholic ingredient separately and add them together.

Frequently asked questions

Why does my country's count differ from the US count?

Because the size of a standard drink differs. The same pint of beer is fewer US standard drinks (14 g each) than UK units (8 g each). Neither is more correct. They're just different measuring sticks.

Is a UK unit 8 grams or 10 milliliters?

Both are used. Ten milliliters of pure alcohol weighs about 7.89 g, so the two are very close. This calculator uses 8 g. A strictly volume-based count would be about 1.4% higher.

Can this tell me if I am under the legal driving limit?

No. Blood alcohol depends on body size, sex, food, timing, medication and how your own body processes alcohol. Estimates can be badly wrong. This tool only measures the alcohol in the drink. If you have been drinking, do not drive.

How do I count a cocktail?

Work out each alcoholic ingredient separately and add the results. For example, 1.5 fl oz of 40% spirit and 0.75 fl oz of 20% liqueur. Mixers without alcohol don't change the total.

How this calculator is checked

Method: Pure alcohol = volume × ABV × 0.789 g/mL (density of ethanol); standard drink sizes of 14 g (US), 8 g (UK unit) and 10 g (Australia). The calculation is covered by automated tests with known reference values and edge cases. Last updated 2026-10-18. Found a problem? Tell us.

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