In a man’s wardrobe, there are few things that are as ubiquitous—and yet confounding—as the polo shirt. No two fit the same. In winter storage they magically change size. Brands like Brooks Brothers are making shirts for different guys than Uniqlo, even if they’re essentially the exact same item.

How do you know which one is right for you?

To figure it out, we devised an experiment: We gathered some 200 polo shirts from 32 brands—all sized medium. Shape and proportion varied wildly. For instance, shirt sleeve lengths ranged from 7.5 inches (Gant Rugger) to 11 inches (Orlebar Brown), and the total length of two garments from collar to bottom hem had a difference of 10 inches. Don’t get us started on belly circumferences. Remember, these are all the same sized shirt!

We then had eight different-bodied men—real men from our office, not models—try on shirts until we found ones that fit. We noted what brands worked and what styles didn’t. Whether you’re tall and skinny or short and athletic, here are our findings.

Mouse over each photo for observations and tips.