Brooks vs Adidas Shoe Size — Which Runs Smaller?
Brooks runs about half a US size large compared to Adidas. If you wear Brooks in US 9, start by checking Adidas in US 9.5. Both brands use the same foot-length measurement — the difference is in the last shape, not the conversion formula.
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Switching rule for this pair
At the US 9 anchor, the same 262mm foot maps to Adidas US 9.5. In plain terms: when moving from Brooks to Adidas, go up half a US size.
- Brooks: true to size signal from 65% of buyer-fit data.
- Adidas: true to size signal from 70% of buyer-fit data.
- If you know your foot length in millimetres, use the Size Passport above before trusting a label-to-label switch.
Brooks → Adidas size chart
| US Men (Brooks) | Brooks → Adidas | Foot length |
|---|---|---|
| 7 | 7.5 | 246mm |
| 8 | 8.5 | 254mm |
| 9 | 9.5 | 262mm |
| 10 | 10.5 | 271mm |
| 11 | 11.5 | 279mm |
Fit verdict
- Brooks: True to size (65% of buyers)
- Adidas: True to size (70% of buyers)
Why the sizes differ
Brooks runs ~0.5 size larger than Adidas.
Brooks foot length is measured in millimetres, then mapped to US size. The Adidas last fits the same foot, but the starting label shifts by about half a US size because of each brand's fit bias — not a different conversion formula.