If you drink wine, there’s a good chance you measure intake by the glass.
Here’s why that’s problematic: Modern wine glasses are seven times larger than those of centuries ago—and notably bigger than glasses that are just two decades old, according to a new study.
Researchers at the University of Cambridge analyzed more than 400 antique and modern wine glasses, including some of various British monarchs, and determined the average and median size of glasses has increased gradually since the 1700s, but with a “more marked” bump in the 1990s, per NBC News.
Centuries ago, wine glasses held about 2.2 ounces on average, reports Quartzy. But by 2000, they held about 10 ounces, per the BBC. Today they hold more than 16 ounces, or about half a liter, according to the study in the British Medical Journal.
Wine consumption has similarly increased, quadrupling in Britain between 1960 and 1980, then doubling again from 1980 to 2004, per the Guardian. Researchers suggest a link between the increased consumption and bigger glasses, arguing that people pour more wine into a larger glass, which makes the amount seem less than if it were in a smaller glass. (The researchers focused on the Brits, but they say that a trend in the US toward bigger glasses likely had an influence.) Some say other factors explain why people are drinking out of larger glasses, with wine expert Miles Beale noting that they allow wine to aerate, “something which perhaps wasn’t a priority 300 years ago.” (Avoid merlot? You might want to reconsider.)