Most of the size increase has happened just in the last 20 years, and in line with our growing interest in wine (and drinking it, of course), say researchers at the University of Cambridge.
The wine glass was introduced around 1700, and the researchers were able to find examples of 411 glasses through the ages. In the early years, average capacity was just 66 ml, and, by 2000, it was 417 ml—but today the average is 449 ml. In other words, a Georgian wine glass would hold just half the amount of wine of today's typical glass.
Although greater wine appreciation is a major driver for the size increase, other factors have also been in play over those 300 years. The Glass Excise Tax in the mid-18th century in the UK would have had a big impact on the size of glasses, and technology—and glass-blowing in particular—would have inhibited the size of a glass. Only when mass production was introduced in the late Victoria era could a wine glass size be increased easily.
But it's our appreciation of different wines, and the way they should be served, that has had the biggest impact on the size of wine glasses.
And if you're a little worried about just how much you're drinking this festive season, remember one useful maxim: you don't have to fill the glass to the top!