👟 Brand to Brand
UGG to On Shoe Size Conversion
Switching from UGG to On? UGG runs large and On runs true to size, so the size you order changes. Here's the full chart.
A UGG 8.5 works out to a On 9 — about half a size up. The chart below has every size.
UGG → On: size up half a size
A UGG 8.5 is a On 9.
Find your UGG size on the left, read across for On:
| UGG size | On size | UK | EU | Foot (cm) |
|---|---|---|---|---|
| 6 | 6.5 | 5.5 | 37 | 23.5 |
| 6.5 | 7 | 6 | 38 | 24.3 |
| 7 | 7.5 | 6.5 | 38.5 | 24.7 |
| 7.5 | 8 | 7 | 39.5 | 25.1 |
| 8 | 8.5 | 7.5 | 41 | 25.9 |
| 8.5 | 9 | 8 | 41.5 | 26.3 |
| 9 | 9.5 | 8.5 | 42.5 | 26.7 |
| 9.5 | 10 | 9 | 43 | 27.1 |
| 10 | 10.5 | 9.5 | 43.5 | 27.5 |
| 10.5 | 11 | 10 | 44 | 27.9 |
| 11 | 11.5 | 10.5 | 44.5 | 28.3 |
| 11.5 | 12 | 11 | 45.5 | 28.7 |
| 12 | 12.5 | 11.5 | 46 | 29.1 |
| 12.5 | 13 | 12 | 47 | 29.5 |
| 13 | 13.5 | 12.5 | 47.5 | 29.9 |
| 13.5 | 14 | 13 | 48 | 30.3 |
| 14 | 14.5 | 13.5 | 49 | 31.1 |
| 14.5 | 15 | 14 | 49.5 | 31.5 |
⚠️ Fit varies by model. UGG runs about half a size large and moulds to the foot — size down half, or a full size for slippers. On (On Running) runs true to size for most, with a snug, performance fit.
On to UGG → · UGG chart · On chart · Brand finder
What is a UGG 8.5 in On?
A UGG 8.5 is about a On 9 — they share a foot length of roughly 26.3 cm (UK 8, EU 41.5).
Do UGG and On fit the same?
No — UGG runs large and On runs true to size, so size up half a size when you switch.
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