How do I know what size running shoes to buy?

Buying the wrong size running shoe can spoil your running experience – here is how to pick the right size, every time

Heavily tattoed runner trying on Craft running shoes
(Image credit: Craft)

Running shoes that fit well can help you run faster and stay injury-free for longer. There are many types of running shoes to choose from, from neutral road running shoes to supportive trail runners, but none of them will be of any use if you don't know how to choose the right size for you.

Running shoe sizing is notoriously inconsistent, which is surprising as you'd think it'll be somewhat similar across all brands, knowing how important it is for running shoes to fit correctly. Sadly, though, that's not the case, and it's easy to get the wrong size of running shoes if you don't pay careful attention.

The good news is that it's equally as easy to get the size right by checking one thing: the length of your feet. Once you know how long your feet are, you can make an educated guess about running shoe sizes. But before you head over to our best running shoes guide and start shopping, read the blow four tips that will help you get the right size running shoes every time.

1. Check both feet

Your left and right foot aren't the same size, believe it or not, hence why you need to measure both. The best way to measure the length is to stand next to a wall with your heels touching the wall and measre the distance from the wall to the end of the big toe. The tape should be perpendicular to the wall. Once you measured both feet, see which is bigger and use that as a bencjmark when buying shoes.

Yellow foot measurement device with foot being measured

If you have one of these devices, it'll make your foot-measurement efforts less complicated

(Image credit: Getty Images)

2. Do the measurement in the afternoon/evening

Another surprising fact is that your feet grow during the day. You might know that your feet can swell up during long runs in the shoes, no matter how ventilated the shoes are. The same thing happens to your feet during the day, especially if you wear shoes throughout the day, so measuring the size and width of your feet late afternoon/early evening is the ideal time to get the most accurate numbers.

3. Check the sizing guide for every shoe

As I mentioned above, size 10 Nike running shoes can be complately different size than a size 10 New Balance. To make matters worse, even models from one brand can be different size, so our best advice is to check the sizing info for every single model before you buy. If you're in between sizes and buying shoes online, order one pair of each size, just to be on the safe side, anmd send back the one that doesn't fit.

SportsShoes.com screenshot


(Image credit: SportsShoes.com)

4. Check the sizing guide at third-party retailers

Third-party retailers usually are impartial about running shoes (in the sense that they don't prefer one brand over the other) and often provide extra information about sizing. For example, Sportsshoes.com (opens in new tab) says it's on the individual product listing page how the shoes fit, according to its testers (see the screenshot above). It's worth having a look around!

+1 check the insole of the shoes you already have

An extra pro tip for you: if you have a pair of running shoes that you know fit well, remove and measure the length of the insole and use that as the benchmark for future shoe purchases. It'll probably have the imprint of your foot already, so you can see exactly how long it is.

It's worth mentioning that if you have issues with your foot poking through the same area of the upper or your toenails falling off, your shoes don't fit well, no matter how much you like them. If the lateral or medial side of the shoes wore away faster, you might need wider fit shoes—a few things to keep in mind.

For more info on what other mistakes to avoid, read our article about the three mistakes everyone makes when buying running shoes.

Matt Kollat
Fitness Editor

Matt is T3's Fitness Editor and covers everything from smart fitness tech to running and workout shoes, home gym equipment, exercise how-tos, nutrition, cycling, and more. His byline appears in several publications, including Techradar (opens in new tab) and Fit&Well (opens in new tab), and he collaborated with other fitness content creators such as Garage Gym Reviews (opens in new tab).