Half Size Up or Down?
When you are between shoe sizes, the safe default is to size up. Size down only when the brand or exact model is known to run large.
Key takeaways
- If the choice is unclear, start with the larger size; lacing, socks and insoles can reduce small extra volume.
- Size down only when the brand or exact model runs large and the larger size slips at the heel.
- A half US or UK size is roughly 4.2 mm of length, so it fixes length more than width.
- For online purchases, prefer retailers with easy returns whenever the fit signal is uncertain.
How to use this guide
Use this page as a decision aid before opening a brand or model guide. The formula gives the starting point; brand fit decides the final choice.
If you already know the brand, open its size guide and compare the fit verdict, width availability and source confidence before buying.
What is the quick rule for half size up or down??
The practical rule is: If the choice is unclear, start with the larger size; lacing, socks and insoles can reduce small extra volume.