How much alcohol is in a glass of whisky?

According to the Trimbos Institute, a standard glass contains about 10 grams of pure alcohol, whether it is beer, wine or spirits.

Each drink has its own quantity. Trimbos cites 250 millilitres of beer at 5 percent, 100 millilitres of wine at 12.5 percent and 35 millilitres of spirits at 35 percent.

The Trimbos standard drinks calculator also lists whisky with a glass of 35 millilitres. For advice on alcohol consumption, we refer to the Trimbos-instituut at alcoholinfo.nl.

Multiply the contents of the glass by the alcohol percentage for the millilitres of pure alcohol, and multiply that by 0.789 for the number of grams.

The number 0.789 is the density of ethanol: one millilitre of pure alcohol weighs 0.789 grams at 20 °C. One millilitre of alcohol therefore weighs less than one millilitre of water.

An example with 35 millilitres of whisky at 40 percent: 35 × 0.40 = 14 millilitres of alcohol, and 14 × 0.789 = 11.0 grams. For the Trimbos standard glass, 35 × 0.35 × 0.789 = 9.7 grams applies, rounded to 10 grams.

European Regulation 2019/787 prescribes in Annex I, category 2, that whisky or whiskey must have at least 40 percent alcohol by volume.

For Scotch whisky, the British Scotch Whisky Regulations 2009 lay down the same minimum of 40 percent, alongside requirements such as at least three years of maturation in oak casks of no more than 700 litres.

A bottle with less alcohol may not carry the name whisky. A glass of 35 millilitres therefore always contains at least 11 grams of alcohol, slightly more than a standard drink.

A glass of 35 millilitres of 60 percent whisky contains 21 millilitres of pure alcohol, about 16.6 grams, just over one and a half times a standard glass.

With cask-strength whisky the percentage is often far above 40 percent; on our shelf, 1,485 whiskies are 50 percent or more. At 50 percent, 35 millilitres contains 13.8 grams of alcohol.

The strongest whisky on our shelf is 73.7 percent; 35 milliliters of it contains 20.4 grams of alcohol. For 10 grams of alcohol, about 21 milliliters is enough at 60 percent, and about 32 milliliters at 40 percent.

The label shows the actual alcohol content as a number with at most one decimal, followed by % vol., optionally preceded by alcohol or alc.

That is prescribed by Annex XII of European Regulation 1169/2011 on food information. For drinks such as whisky, the actual content may deviate by 0.3 percent vol from the figure on the label.

With the percentage and the volume of the bottle you calculate the total amount. A 70 centilitre bottle of 40 percent contains 280 millilitres of pure alcohol, about 221 grams, and fills twenty glasses of 35 millilitres.

Of the 3,883 whiskies on our shelf, 601 are exactly 40 percent, 1,750 are between 40.1 and 49.9 percent and 1,485 are 50 percent or more.

Converted, over 15 percent of the whiskies have the legal minimum, about 45 percent sit between 40 and 50 percent and over 38 percent sit at 50 percent or higher. Of 810 whiskies the percentage is 55 percent or more.

Anyone who wants to know how much alcohol is in a glass from a particular bottle can have the percentage looked up at the counter. We do not sell spirits to people under 18.