A standard single serving of wine is 5 fluid ounces, yet is that five-ounce portion what you typically pour yourself? Could the shape or size of your wine glass actually cause you to pour more or less than the five-ounce standard? A recent study examined whether people pour more wine into a wider glass compared with a somewhat thinner glass, and also whether they pour more based on whether the wine is red or white. Results found that, on average, people tend to pour more wine into a wider glass (12% more) than a thinner glass and they tend to pour more wine when it is white rather than red (9% more), regardless of the glass shape.
Why might this be so? Past research indicates that when people are estimating how much liquid is in a clear container, they pay more attention to the height of the liquid than its width. Hence, a wider glass receives a larger pour than does a thinner glass. Past research also finds that people tend to consume more food and drink when it has a lower color contrast with the container it is in. Hence, when a wine glass is transparent, people will tend to consume more white wine than red wine, which also likely explains why they make larger white wine pours.
The fact that standard “red wine” glasses tend to be appreciably wider than standard “white wine” glasses would seem to cancel out these two factors in wine pouring. So, if you want to drink less wine, maybe you should consider serving red wine in standard “white wine” glasses. In contrast, if you want to encourage greater wine consumption, reverse this process by serving white wine in standard “red wine” glasses. Or ignore these findings and simply enjoy your wine!