In a world of 44-ounce Big Gulps and restaurant entrees that can be triple a healthy serving size, it’s important to have a good eye for healthy portions.

But if you’re constantly exposed to ginormous servings, your sense of normal can be thrown way out of whack. That’s what I learned while taking this cool interactive Supersize Soft Drink quiz from the New York Times. According to a related study of 294 subjects, it turns out that people are really bad at gauging increases in portion size—we tend to assume that bigger cups hold 20 to 40 percent less liquid than they actually do. Test yourself and tell us: How did you do?

Also: 9 offensively enormous beverages, and what you could be eating instead »

Photo: © Bradley Stemke/Flicker Commons