👟 Brand to Brand
Under Armour to On Shoe Size Conversion
Switching from Under Armour to On? Under Armour runs small and On runs true to size, so the size you order changes. Here's the full chart.
Under Armour runs 0.5 size larger than On, so you may need to size down when switching.
Size up 0.5 moving to On
On runs smaller — order half a size larger than your Under Armour size.
Find your Under Armour size on the left, read across for On:
| Under Armour size | On size | UK | EU | Foot (cm) |
|---|---|---|---|---|
| 6.5 | 6 | 5.5 | 37 | 23.5 |
| 6.5 | 6 | 5.5 | 37.5 | 23.9 |
| 7 | 6.5 | 6 | 38 | 24.3 |
| 7.5 | 7 | 6.5 | 38.5 | 24.7 |
| 8 | 7.5 | 7 | 39.5 | 25.1 |
| 8 | 7.5 | 7 | 40 | 25.5 |
| 8.5 | 8 | 7.5 | 41 | 25.9 |
| 9 | 8.5 | 8 | 41.5 | 26.3 |
| 9.5 | 9 | 8.5 | 42.5 | 26.7 |
| 10 | 9.5 | 9 | 43 | 27.1 |
| 10.5 | 10 | 9.5 | 43.5 | 27.5 |
| 11 | 10.5 | 10 | 44 | 27.9 |
| 11.5 | 11 | 10.5 | 44.5 | 28.3 |
| 12 | 11.5 | 11 | 45.5 | 28.7 |
| 12.5 | 12 | 11.5 | 46 | 29.1 |
| 13 | 12.5 | 12 | 47 | 29.5 |
| 13.5 | 13 | 12.5 | 47.5 | 29.9 |
| 14 | 13.5 | 13 | 48 | 30.3 |
| 14 | 13.5 | 13 | 48.5 | 30.7 |
| 14.5 | 14 | 13.5 | 49 | 31.1 |
| 15 | 14.5 | 14 | 49.5 | 31.5 |
⚠️ Fit varies by model. Under Armour tends to run about half a size small, especially in performance trainers. On (On Running) runs true to size for most, with a snug, performance fit.
On to Under Armour → · Under Armour chart · On chart · Brand finder
What is a Under Armour 10.5 in On?
A Under Armour 10.5 is about a On 10 — they share a foot length of roughly 27.5 cm (UK 9.5, EU 43.5).
Do Under Armour and On fit the same?
Not quite — On runs about 0.5 size smaller than Under Armour.
ⓘ Affiliate links below. As an Amazon Associate we earn from qualifying purchases at no extra cost to you.
Recommended on Amazon
Foot Measuring Device
Measure once, buy any brand with confidence.
View on Amazon →