Should you buy running shoes a size bigger? The answer isn't simple. Learn why bigger isn't always better, how to find the perfect fit, and what really causes foot pain while running.
Running Shoe Sizing: How to Find the Right Fit for Your Feet
When it comes to running shoe sizing, the process of selecting the correct shoe dimensions to match your foot shape and movement. Also known as footwear fit, it's not just about picking a size that feels okay—it's about preventing blisters, shin splints, and long-term damage. Too many runners grab the same size they wear in casual shoes and wonder why their feet hurt after a mile. The truth? Your running shoe should be half a size to a full size bigger than your everyday shoes. Why? Because your feet swell during runs, especially on longer distances.
Your foot measurement, the actual length and width of your foot, taken at the end of the day when it's largest is the only real starting point. Don't trust what your last pair said. Measure both feet—most people have one foot larger than the other—and base your choice on the bigger one. running shoes, specialized footwear designed to support impact, stability, and forward motion during running aren't one-size-fits-all. A shoe that fits well in the heel and midfoot but leaves room for your toes to spread is the sweet spot. If your big toe is jammed against the front, you're asking for black toenails or neuromas.
Brands vary wildly. A size 9 in Nike might feel like an 8.5 in Asics and a 9.5 in Brooks. That’s why trying shoes on in person, preferably after a short walk or jog, matters more than any online chart. Look for about a thumb’s width of space between your longest toe and the end of the shoe. Your heel shouldn’t slip. Your arch should feel supported, not crushed. And don’t forget width—many runners ignore it until their toes feel squeezed. Wide feet need wide shoes, not just a bigger length.
What you wear on your feet affects everything: your stride, your recovery, your ability to keep running. A bad fit can turn a fun jog into a painful chore. The right sizing doesn’t just help you run farther—it helps you run longer without quitting. Below, you’ll find real advice from runners who’ve been there: how to test fit, which brands run true, and why your shoe size might change over time as your feet adapt to training.