How much alcohol is in a gin and tonic?

A gin and tonic with 35 milliliters of gin at 37.5 percent contains 13.1 milliliters of pure alcohol, or 10.4 grams: roughly one standard drink.

The calculation has two steps. First the measure of gin times the percentage: 35 times 0.375 is 13.125 millilitres of pure alcohol. Then the weight: pure alcohol weighs about 0.789 grams per millilitre, so 13.125 times 0.789 is 10.36 grams.

Because a standard glass is 10 grams of pure alcohol, that gin and tonic works out at 1.04 standard glasses. The tonic does not count in this sum, because it contains no alcohol itself.

A standard glass of alcohol in the Netherlands contains 10 grams of pure alcohol, which at a density of 0.789 grams per millilitre comes to about 12.7 millilitres of ethanol.

The Trimbos-instituut describes one unit of alcohol as a standard glass with roughly 10 grams of ethanol. The Voedingscentrum lists the measures per drink: beer of 5 percent in 250 millilitres, wine of 12 percent in 100 millilitres and spirits of 35 percent in 35 millilitres. Calculated out, those three contain 12,5, 12.0 and 12.25 millilitres of pure alcohol, so 9,9, 9.5 and 9.7 grams.

Gin legally starts at 37.5 percent and so sits just above the 35 percent used for that standard measure. A 35 millilitre measure of gin therefore delivers slightly more than a standard glass. What the percentage on the label indicates can be found on the page about abv and proof.

The amount of pure alcohol scales in direct proportion to the measure of gin and to the alcohol percentage: a quarter more percent gives a quarter more alcohol in the glass.

With 35 millilitres of 47 percent gin, that is 16.45 millilitres of pure alcohol, 12.98 grams and 1.30 standard glasses. A larger measure works the same way: 50 millilitres of 37.5 percent gin gives 18.75 millilitres of pure alcohol, 14.79 grams and 1.48 standard glasses. When a generous measure and a high percentage come together, it counts double: 50 millilitres of 47 percent comes to 23.5 millilitres of pure alcohol, 18.54 grams and 1.85 standard glasses.

In Bathmen there are 255 gins on the shelf, with percentages from 37.5 to 48.2. For a measure of 35 millilitres, the result across that whole range therefore runs from 1.04 to 1.33 standard glasses. How much gin you put in the glass is a different question; the page on how much gin goes into a gin and tonic deals with that.

35 milliliters of gin at 37.5 percent in a glass with 200 milliliters of liquid comes to about 6.6 percent by volume.

The sum is 13.125 milliliters of pure alcohol divided by 200 milliliters, times one hundred: 6.56 percent. With a gin of 47 percent that becomes 16.45 divided by 200, so 8.22 percent.

A larger glass dilutes further. 50 millilitres of gin at 37.5 percent in 250 millilitres of liquid gives 7.50 percent by volume, and 25 millilitres of gin at 37.5 percent in 200 millilitres stays at 4.69 percent. Melting ice increases the volume and therefore lowers the percentage, while the amount of pure alcohol in the glass stays the same. Why a lot of ice goes in is explained on the page about plenty of ice in a gin and tonic.

The Voedingscentrum advises not drinking alcohol, and if you do drink, no more than one glass a day.

That one glass is the standard glass of 10 grams of pure alcohol. A gin and tonic with 35 millilitres of gin of 37.5 percent is just above it at 10.36 grams; with 50 millilitres of 47 percent a glass is already at 1.85 standard glasses.

Alcohol en autorijden gaan niet samen. De Wegenverkeerswet 1994 legt in artikel 8 de grens op 0,5 milligram alcohol per milliliter bloed of 220 microgram per liter uitgeademde lucht; voor beginnende bestuurders is dat 0,2 milligram en 88 microgram. Wij verkopen geen alcohol aan mensen onder de 18 jaar: NIX18.

Yes, with alcohol-free gin and tonic the make-up of the drink stays the same, but the gin supplies no pure alcohol to the glass.

The calculation thus falls away: the measure stays 35 or 50 millilitres, but the percentage you multiply by is zero or almost zero, so no standard glass remains to be counted.

We have alcohol-free gin in the shop on the Brink in Bathmen. What lies behind it in terms of preparation and rules can be found on the page about alcohol-free gin.