Why Same-Size Running Shoes Aren't Always the Same Size

AT THE 2021 Boston Marathon, I felt a flash of pain in my left foot. Despite the searing burn on my toes, I managed to run just two minutes shy of a sub-three-hour race.

- AMANDA FURRER

My ivory shoes were still white, save for a copper-colored streak. A friend initially thought the blotch was part of the shoe's design. It was dried blood.

Racing in the wrong shoe size is a rite of passage for new runners and a rookie mistake for vets like me.

But hang on-I'm not the only one at fault here. As a Runner's World gear editor, I've noticed fit, length, and width can vary among a single brand's different shoe models, even when the sizes on their boxes are the same. So, what's going on with shoe sizing?

To find out, I spoke with runner and FleetFeet content marketing specialist Caroline Bell-a former FleetFeet sales associate, she's worked on the retail side, too-and podiatrist and performance footwear consultant Simon Bartold.

TRY THIS ON FOR SIZE

"Sizing generally is a nightmare, with no universal system," said Bartold, who was an Asics research consultant. He noted how the three major sizing systems-U.S., U.K., and European-are completely different. A men's U.S. 9, for example, is a U.K. size 8 and European size 42.

"In addition, length and width basically do not talk to each other. So, going by measurement in itself a Pandora's boxyou may be a U.S. 7, but you might need to go to a U.S. 9 or 10 to get satisfactory width fitting," said Bartold. "Likewise, it can go the other way if one has a narrow foot. A measured U.S. 7 might need to go down to a U.S. 5 to stop slippage."

One way to find a secure fit is to try a shoe in different widths. The standard width is D for men and B for women. Some specialty running shops carry other widths to accommodate runners who don't fit the industry standard. FleetFeet stores, for instance, tend to carry wider EE widths for men and D widths for women, but you should call the store beforehand, said Bell, to make sure they have those or other widths in stock.