Adidas and ASICS assign different EU numbers to the same US size. Runners swapping brands should match foot length in centimeters, not copy the EU number. US and EU sizes are two numbering systems for the same heel-to-toe length. Adidas lists men's US 8 as EU 41 1/3 at 25.5 cm, according to the Adidas size chart, while ASICS lists men's US 8 as EU 41.5, according to the Step With Shoes ASICS chart.
Medical information disclaimer: This article is for general educational purposes only and does not provide medical advice, diagnosis, or treatment. Always consult a physician or other qualified health professional about symptoms, medications, tests, or treatment decisions.
Table of Contents
- Why does the same US size show a different EU number?
- How do you switch brands without misfitting?
- How should you measure your feet?
- What width and fit changes should runners expect?
Why does the same US size show a different EU number?
Each brand maps US sizes to its own EU scale. Adidas pairs men's US 8 with EU 41 1/3 and men's US 8.5 with EU 42 at 25.9 cm. ASICS pairs men's US 8 with UK 7 and EU 41.5, and men's US 9 with UK 8 and EU 42.5.
That offset means the EU number alone does not transfer between brands. A runner with a 25.5-cm foot needs the Adidas label for 25.5 cm and the ASICS label for the same length. Use centimeters as the common reference.
How do you switch brands without misfitting?
Start from your measured foot length and current US size. If your Adidas US length gives enough toe room, look for the ASICS US size with the closest centimeter match rather than the same EU mark.
Consider width as well as length. Direct comparisons report Adidas runs slightly narrower, especially in the midfoot, so Adidas wearers moving to ASICS often find more width without changing US length, according to RunnerClick in its ASICS fit guide. Do not size down to chase a familiar EU number.
How should you measure your feet?
Adidas advises measuring at the end of the day from big-toe tip to heel outer edge. Choose a tighter fit by sizing down around that measurement and a looser fit by sizing up.
For a home check, reviewers recommend a wall method: This method captures the longest toe, which may not be the big toe. Measure wearing the socks used for running.
- Stand with heel against a wall on paper.
- Mark the longest toe, then measure wall to mark.
- Repeat for both feet and use the larger foot.
What width and fit changes should runners expect?
ASICS running models generally fit true to US size, but standard widths can feel slightly narrow. The brand offers Narrow, Standard, Wide 2E, and Extra-Wide 4E in many styles.
Fit also varies by model, socks, orthotics, and swelling. Leave about a thumb's width ahead of the longest toe and confirm the specific model's chart before ordering.