Skip to main content


Share this post

Choosing the right size of your trail running shoes is essential to guarantee the right protection, cushioning, stability and, above all, to reduce the risk of blistering and the formation of black nails in the toes.

How can you easily calculate the perfect size of your trail running shoes without making a mistake? Have a look at the Mini-Guide below.

Mini-Guide for calculating the correct size for your trail running shoes

If you are about to buy your new trail running shoes on the internet, without being able to try them in the store, you may find yourself in difficulty in determining the correct shoe number.

Let’s see how you can find the right size of the new trail running shoes without making a mistake.

Case 1. You already have an old pair of trail running shoes with which you felt comfortable and that did not cause you any problem, but you are about to purchase a different brand.

On the inside of your shoe tongue, in addition to the reference size for the different countries (EU, UK, US), you find the internal length of your shoe expressed in centimeters (CM or more rarely JP). Use the centimeters to find your corresponding shoe number for the new shoe as it is the only comparable parameter.

Case 2. You can’t find the centimeters of your old trail running shoe or you don’t have a pair of running shoes with you?

You can find the right size by measuring the length of your foot. How to do it?

Here are the 5 steps to calculate your foot length.

  1. Place a sheet of paper on the floor with one side flush against a wall.
  2. Then place one foot on top of the paper with your heel against the wall.
  3. Draw a mark at the end of the longest finger, then measure the lenght from the mark to the edge of the paper.
  4. Add 1 or 1.5 centimeters to the measured length (if you run ultra trails we recommend adding 1.5 centimeters because the feet, after many kilometers start swelling).
  5. Choose the size of your new shoes based on the calculated centimeters and the number, by excess, that comes closest.

At this point, you have found the right size and you can proceed with the purchase of your new adventure companion … good training and good races!

Would you like more tips on how to choose trail running shoes? Maybe you may also be interested in:

  • the checklist for the perfect purchase of the trail running shoe, click HERE
  • what is the drop and which is the right one for your trail running shoes, click HERE

Would you like to chat with a TRM Coach? Contact us here TRM Coach


how to buy trail running shoes, tips trail running shoes, trail running products, trail running shoes, trail running shoes, trail running shoes, trail running shoes size

Cristina Tasselli

Digital Strategic Marketing Director - certified Innovation Manager - in multinational companies, she is still today the only Italian female athlete to have ran 900 km and 55,000m D+ in the mountains in a single stage race (Transpyrenea 2016, 3rd women overall). She counts numerous Podiums and international Victories on races over 100k. She holds a SNaQ CONI certification as a Trail Running Coach, Athletic Trainer and in Nutrition and Sports Supplementation. Since 2014 she is President and sports executive of innovative technology startups and companies, including Trail Running Movement and Digital Sport 360. She trains elite trail running athletes and she teaches in trail running coach certification courses. She is an author of sports articles on training, nutrition and supplementation in trail running and running, both in Italian and in English and Spanish. She manages relationships and collaborations with Federations and Race Organizers.