The Real Difference Between a 9.5 and 10 Shoe

What’s the real difference between a 9.5 and 10 shoe size? We’ve all been there: the size 10 in the kicks you’ve got to have are sold out and you have to make a game-time decision on whether the 9.5 will work. The short answer is the size difference is noticeable.

In this article, we’ll sink our toes into shoe sizing. We’ll cover a little history, discuss the degree of difference between sizes, the health effects of the wearing the wrong size, how to measure your foot, and what causes differences in size between brands.

A Brief History of Shoe Sizing

The English linear system was introduced in 1324 by King Edward II and became the standard measure of shoe size. The difference between sizes was (weirdly) called a “barleycorn.” That difference measured at ⅓ of an inch (8.47 mm). Half sizes weren’t introduced until 1880, and they differed ⅙ of an inch.

The Paris point (now know as the EU sizing system) was introduced in the mid 19th century. Full shoe sizes measure in at 6.67 mm. Most notably, though, these don’t come in half sizes.

Brannock foot measuring instrument patent photo.

The American system was developed in the 19th century as a hybrid of the English and Paris point methods. The difference between half sizes in the US system is about 4.23 mm. Typically, though, an American shoe runs one size smaller than a comparable English shoe. So, an American size 11 translates roughly to an English size 10.

On the surface, there’s little difference between a 9.5 and 10 shoe. However, small is far from negligible.

Measuring Your Shoe Size

The best way to avoid even wondering about the difference between 9.5 and 10 shoe sizes is simply to measure your foot. You can do this at home with this guide:


  1. Start with a blank sheet of paper on a flat, hard surface. A ‘pro move’ is to tape it the surface. It’s extra secure- no slippage.
  1. Use a writing utensil to trace the outline of your foot. You can do this either barefoot or in socks, but we recommend however you intend to wear your shoes.
  1. Once traced, use a ruler or straight edge to draw straight lines at the outermost edges of the foot. This creates a box around your tracing.
  1. Use a ruler to measure the length of your foot from the furthest two points. This should be where those straight lines intersect with your tracing- it will usually be from heel to big toe. Do the same for the width and record the widest measurement, usually across the balls of the feet.
  1. Then, use the measurements on this chart to find your correct shoe size.

A Chart Comparison

Measurement (in.)US Shoe Size (Mens)UK Shoe Size (Mens)European Shoe Size (Mens)
9 1/465 1/239
9 1/26 1/2639
9 5/876 1/240
9 3/47 1/2740/41
9 15/1687 1/241
10 1/88 1/2841/42
10 1/498 1/242
10 7/169 1/2942/43
10 9/16109 1/243
10 3/410 1/21043/44
10 15/161110 1/244
11 1/811 1/21144/45
11 1/41211 1/245
11 9/161312 1/246
11 7/81413 1/247
12 3/161514 1/248

Make sure to note that different size charts may vary slightly on the measurement. That is why it’s important to try before you buy when deciding between half sizes!

You’ll also notice that the European sizes again force you with the option to decide since there are no half sizes. Trying both sizes in the same shoe (and returning the ill-fitting pair if purchased online) is our recommendation to find your fit.

For Women’s US sizing, a men’s size 6 would be a women’s size 7.

Which Shoe Size to Choose

If you’re in a bind and need the shoe, conventional wisdom leans toward sizing up. That’s especially true when trying on shoes at the end of the day when your feet are at their largest. It’s also easier to wear a larger shoe. Slipping sneaker inserts or tongue pads into dress shoes work wonders; thick, Irish wool socks are an excellent companion to cordovan boots.

Shoe Sizing and Fit Fundamentals

The most important fit element is to ensure the arch of your foot aligns with the arch in the shoe. That way, you’ll get the maximum support from the shoe.

This means, though, your sizing will vary: not all shoe brands use the same sizing system. A half size here or there can throw off this balance and lead to considerable discomfort.

Length and Width

There’s more to a shoe size than length. How wide your foot is also important to ensuring proper fit. In the United States, an ‘average’ foot is of a “D” width. A ‘narrow’ foot ranges from “A” to “C” widths, and a ‘wide’ foot ranges from “E” to “EEE.”

In UK, however, a standard width is an “F”, with “E” being narrow and “G” being wide.

9.5 vs 10 shoe size. usa vs europe size comparison.

So, if the shoemaker in question offers shoes in additional widths, you may want to consider getting measured for that as well.

Most companies today- especially the burgeoning direct-to-consumer brands- offer D and E width shoes.

If you’re a narrow width, however, consider taking a 9.5 instead of a 10 shoe. Conversely, if you’re a wider width, you may consider taking a 10.5.

Where you Wear Matters!

Where and how will you be wearing your shoes?

In the summer, a shoe that slips off with each step, particularly the ones you wear with no-show socks or sockless, is as annoying as it is uncomfortable. In those cases, a half size down is ideal to ensure comfort and reduce slippage.

With a running shoe, you may consider sizing up a half size to account for how your feet will swell from pounding the pavement.

In shoes with leather uppers, sizing down a by a half size will allow you to stretch the shoe and mold it to your foot shape upon each wear. You can also use shoe trees to do this. If that’s your plan, initial discomfort will be part of the process.

But, all the stretching and wearing won’t make it more comfortable it’s simply completely too cramped to begin with. If your toes are stuck together in the shoe, consider a half size up.

Half Shoe Size and Foot Health

The College of Podiatry conducted a study of 2000 adults in which one-third of men and close to half of women admitted they purchased ill-fitting shoes.

Ill-fitting shoes can result in a host of health problems. Aside from bunions and deformities, continuous wear of poorly fitting shoes can lead to back pain and headaches.

brown suede lace shoes

Moral of the story, the difference in the half size between 9.5 and 10, or any sizes, can be a serious issue. It’s something to consider if you’re deciding on whether that little discomfort is worth it when your shoe size isn’t available. It’s also why taking the larger size of two is usually recommended.

Shoes Sizes Vary Brand to Brand

The last point to consider is many brands follow different sizing methods. An Adidas running shoe in a 9.5 will fit differently than an Allen Edmonds Park Avenue oxford in the same size.

Different manufacturers use different lasts-the shape around a shoe is molded. A longer last will have a longer toe box- which may necessitate taking a smaller size. They may also use different sizing systems depending on where they are manufactured. So, a John Lobb ‘William’ double monk strap will sit differently than an Allen Edmonds St. John’s monk will.

So, you’re most likely not going to be a size 9.5 or size 10 universally from shoe brand to shoe brand. It’s important, then, to consider a variety of sizes from a variety of brands.

If it’s your first time ordering from a European shoe company- consider ordering the size you think you are as well as size smaller. Then, you can choose which is the better fit based on your personal preference.

Final Thoughts

Initially, the difference between a 9.5 and 10 shoe appears minimal, but in truth comfort is paramount. Prolonged discomfort can lead to podiatric trouble.

You will notice a difference in that half size. When deciding which to buy if you’re in a pinch, consider how often you’ll be wearing the shoe, what conditions, and how you’ll be wearing it.

Try not to commit to a shoe size if you’re on the fence without trying the shoe first. If you’re buying online, you can return and exchange!

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