OPTCLA Running Shoe Size Guide
OPTCLA AeroMax Runner is sold in EU sizes 44-52. Use this guide to compare approximate US men's sizes and choose a fit that feels secure, cushioned, and comfortable for daily road running.
EU to US men's size chart
| OPTCLA size | Approx. US men's size | Fit note |
|---|---|---|
| EU 44 | US Men's 10.5 | Best for customers who usually wear 10-10.5 in running shoes. |
| EU 45 | US Men's 11.5 | Choose if your usual running shoe is around 11-11.5. |
| EU 46 | US Men's 12 | Good for a standard US 12 running shoe fit. |
| EU 47 | US Men's 13 | Allows a secure heel feel with room through the forefoot. |
| EU 48 | US Men's 14 | Built for customers who need more length and front-foot comfort. |
| EU 49 | US Men's 15 | Choose for a larger daily running fit with toe movement space. |
| EU 50 | US Men's 16 | Designed for customers who typically need extended men's sizing. |
| EU 51 | US Men's 16.5 | Consider this size if EU 50 feels short or tight at the toes. |
| EU 52 | US Men's 17 | The largest current OPTCLA size for extended comfort fit. |
How to choose your running shoe size
For daily running, the shoe should feel locked in at the heel without pressing tightly across the toes. A small amount of space at the front helps your foot move naturally as you land, roll forward, and push off.
If you are between two sizes, prefer a roomier running fit, wear thicker socks, or often feel pressure near your toes, choose the larger size. If your heel slips easily or you prefer a closer fit, choose the smaller size.
Measure your foot before ordering
Stand on paper with your heel against a wall, mark the longest toe, then measure from the wall to the mark. Repeat with both feet and use the longer foot as your reference. Feet can expand slightly during longer runs, so measure later in the day when possible.
Fit checklist
- Heel feels stable without rubbing.
- Midfoot feels supported but not squeezed.
- Toes can move naturally inside the forefoot.
- Cushioning feels centered under your stride.
- No sharp pressure points after walking indoors.
Need help choosing?
If you are unsure which size to select, contact OPTCLA support before ordering. Include your usual US men's running shoe size, your foot length if measured, and whether you prefer a snug or roomy fit.