Shoe Comfort

Should you change your sample size?

April 22, 2022

Working with hundreds of footwear brands from around the world provides Heeluxe a lot of data on the sample sizes that brands are using. Between 2010 and 2020 the sample sizes were very consistent across brands: almost everyone used a M9 US for Men’s, W7 US for Women’s casual and athletic, and W6 for Women’s fashion. Over the past 3 years we’re observing a major change in sample sizes from our clients. This blog will analyze the changes in sample sizes, why brands are changing their sample sizes, and if you should change your brand’s sample size.


Function and Comfort tests at Heeluxe utilize human testers and provides the best insight into sample sizes. Starting in 2019, it’s easy to see that the majority of women’s footwear tests are Womens 7US (34%) followed by Womens 6US (30%). These numbers are consistent with the years prior to 2019.

Evaluating our women’s studies from 2021 shows a major shift in the women’s sizes for our testing. There was a massive reduction in Women’s size 6US testing, while there is a concurrent increase in Women’s Size 8 testing (59%). In three years Women’s 8US has become our most popular size for testing, even outpacing the “standard” Women’s 7US. We also notice this change in the requests for SmartLast testing, where W8US is our most commonly requested test, followed by W7, and we have not received a request for W6 testing in 9 months!

For Men, it’s easy to see that Men’s 9 US is the most commonly requested test size in 2019 with 70% of our test volume. Men’s 11US is the second most requested test size, representing 16% of our study volume.

In 2021, we see little change in the percentage of Men’s studies using M9 (70%). It’s clear to see that M9 is the dominant sample size in our lab.


There are many reasons why brands are opting to change their sample size. Here are the most common reasons we hear for the change from our customers:

  1. Women’s size 8US is closer to the middle of their size run. Sampling in W8 makes it easier and more accurate to scale their sizes from w5-w11.
  2. There are more Women that wear a size 8, so it is easier to find testers for fit and wear studies (note: we find this to be true at Heeluxe as well. It’s much easier to find testers that wear a w8 for all footwear categories!)
  3. Fashion brands are testing less during COVID. We’ve seen a steady decrease in the number of w6 flats, high heels, and other classic fashion models since the start of the COVID pandemic. Additionally, fashion brands are producing more sneaker styles that they are testing with Heeluxe. This shift to sneakers has allowed them to shift to W7 or W8 sample sizes for the same reasons previously listed.


There is a shift in certain categories of footwear testing larger men’s sizes, but that is offset by other categories testing in M9. For instance, we observe an increase in the number of men’s running brands testing in M10 or M11, but this is offset by increased numbers of casual and occupational shoes being tested in M9. Depending on the category of shoes you are producing, you may consider increasing your sample size to M10 or M11 to make it easier to find wear testers.


If you are making your samples in w6, there are sufficient reasons to increase your sample size to W7 or W8US. It will be easier to gather testers and you’ll likely have better fit in your larger sizes as your fit testing informs your size grading. Note: we’re aware that marketing and sales teams prefer the smaller sizes; fashions brands that have shifted to another size are not seeing any negative impacts in this realm.

If you’re making Men’s running shoes, increasing your sample size to M10US or M11US is ideal for recruiting testers. For casual, hiking, lifestyle, occupational, cleated, or any other category, M9US or M10US is sufficient for sample size.

Note that this data is a fair representation for brands in Europe, North America, and South America, where most of Heeluxe’s customers are from. However, the Asian market may benefit from different sample sizes (and different shape!) to get the best data from their sample testing.

Questions about sample size or how to run testing on your samples? We’d love to help you make better shoes. Please contact Heeluxe via email at