So...What's My Shoe Size?

This short post is distilled out of a discussion over on the Slowtwitch Forums about wide-fitting racing flats. The first thing I noticed was: a lot of people are posting about being 2E or 4E width (that's wide and extra wide widths for men, for those who don't speak running-shoe-ese). And the second was my wonder if people were actually buying the correct size shoe.

In the course of my career in the shoe industry, I've noticed that more often than not I'm changing people's shoe size. Well, let me qualify that: I'm changing a person's running shoe size. I put the emphasis on running shoe size here because, well, it doesn't translate into any other shoe that you wind up purchasing.

This post is for you if you answer one of these questions in the affirmative:

• Have you ever suffered from bruised toes or black toenails during the course of running?
• Have you ever felt like the arch in the shoe has been in the wrong place?
• Have you felt like there isn't enough room in the toebox of the shoe?
• Have you felt like shoes haven't been deep enough, pressing down over the instep and not wrapping the middle part of your foot?

This post won't go into gait analysis and pronation rate, as they don't relate to the sizing of your shoe.

A running shoe is comprised of three distinct measurements that, when taken together, will result in the "true" size that you'll be looking for. Of course, there's variation in manufacturers and how they size. As an example, Brooks shoes currently size about a half-size smaller than they are. So, in their line, take the number that we compute here and add a half-size to it to get the correct "true" size. However, most major brands do now fit true to size.

We'll analyze each piece of the correct sizing spectrum in turn. To get there, though, you'll need to have access to a Brannock Device. A Brannock, you ask? It's one of these old school things:

The Original Brannock Device (courtesy of the Smithsonian Institute).

So, visiting your favorite local running retailer is always a good idea to have them do this sizing for you.

Part I: Foot Length

Yes, this is the part that you should know by now, although often I'm still finding people get this wrong. But, at any rate, it's pretty self-explanatory: we're looking for the total length of your foot here. 

To do this correctly, make sure you are standing with even pressure on both feet. Also, ensure that you're sitting in the back heel cup of the device. Finally, allow the person doing the measuring (yes, somebody else needs to read it!) to measure both feet. We aren't symmetrical! One of your feet will be larger than the other. 

Part II: Arch Length

Here's where things get more difficult, and this is typically where people go wrong with their running shoe size.

In the picture of the Brannock Device up above, you can see a small slider on the upper part of the photo. This is the arch length measurement tool. We're looking for the length of your foot from the heel to the ball of your foot.

To do this correctly, remain in place from the foot length measurement. The fitter will then slide this tool to the center of the ball of your foot. Note that we are looking for the joint itself, and not necessarily where the pad of the foot is. Perform for both feet.

More often than not, we have longer arches than we do physical foot lengths. I'm a shining example of it: size 11.5 length foot, size 13.5 arch. Basically, to put it bluntly, I have short toes versus the length of my foot. Whether that's genetics, or mechanics of the foot at play, I'm not quite certain. But I can tell you the appropriate shoe size from this.

So, what do you do? There are two rules here, depending on the amount of gap between the two numbers generated:

• If the arch length and foot length are within one-half size of each other, simply choose the larger of the two numbers. This is your running shoe size for length. However:
• If the arch length and foot length have a greater discrepancy than a half-size, take the two numbers and average them; this is your running shoe size for length.

Part III: Width of the Foot

Now that we know the correct length, we can correctly size for width. After all, width changes proportionally to the length of the shoe being purchased. Take the appropriate length from above, and use the bottom slider from the picture above to touch the foot; it will then give a corresponding width based on length.

That's it! With those numbers in hand, you should be able to find something that will feel a bit better on foot. Of course, visiting your favorite specialty running store will be advantageous in making sure that you also get the right type of shoe on foot.