Size Matters

How the shape of your glass influences your perception and the amount of alcohol poured.

Posted: Wednesday, April 01, 2015



Size Matters

How the shape of your glass influences your perception and the amount of alcohol poured


In 2005, Cornell Professor Brian Wansink performed a study on the correlation between glass size and the amount of alcohol poured. What he discovered was that, on average, twenty to thirty percent more liquor was poured into short, tumbler type glasses than tall, slender highball type glasses. The study was conducted on both college students and professional bartenders, with results similar across the board.


The college students were broken up into two groups. One was given ten practice tries to pour a standard 1.5oz shot and then instructed to pour four spirits with the same amount into both the tall glasses, as well as short, wide glasses. The other group was asked to do the same without the practice rounds. Although they had practiced ten times, the first group of students still poured an average of twenty-six percent more alcohol into the wider glasses, while the other group of students poured about thirty percent more into the same glasses.


Next, the professional bartenders (average six years in the industry) were broken up into two groups: one group was told to pour four different shots into the two different glass types, and the other group of bartenders were told to do the same, but “take their time.” Surprisingly, the first group of bartenders still poured an average of twenty percent more into the wide, shallow glasses, and the bartenders who took twice as long to prepare the drinks still poured an average of ten percent more. The tendency on all these groups was toward over pouring in the wide glasses, rather than under pouring into the tall, slender glasses.


What’s the reason for this? "People generally estimate tall glasses as holding more liquid than wide ones of the same volume," Wansink said. "They also focus their pouring attention on the height of the liquid they are pouring and insufficiently compensate for its width."


Using this math, if a person receives two drinks in a tumbler, they are actually receiving two and a half. Alarmingly, it appears that despite education, practice, concentration and experience, all groups still over poured in the short, wide glasses. What does this mean for your bar? Whether you see the glass as half full, or half empty, using tall, thin glasses will result in an average of bartenders pouring 20% less, and your patrons believing they are drinking more.


If you’d like to read the entire study, it can be found here: