True-to-Size Millimeter Sizing Comparison
Allbirds Wool Runner vs Saucony Cohesion 17
Detailed size conversion chart, cavity measurements in millimeters, and crowd-sourced fit advice for choosing your perfect size.
Interactive Size Converter
Select what size you wear in the Wool Runner to see your calculated size in the Cohesion 17.
Complete Size Conversion Matrix
Direct millimeter-calibrated mapping comparing all available sizes between both shoes.
| Wool Runner (US) | Internal Cavity | Cohesion 17 Equivalent | Match Accuracy | Fit Difference |
|---|---|---|---|---|
| US 3.5 | 236 mm | US 3.5 | 53% | +4.0 mm |
| US 4 | 239 mm | US 3.5 | 88% | +1.0 mm |
| US 4.5 | 243 mm | US 4 | 100% | 0.0 mm |
| US 5 | 246 mm | US 4.5 | 88% | +1.0 mm |
| US 5.5 | 249 mm | US 5 | 88% | +1.0 mm |
| US 6 | 253 mm | US 5.5 | 100% | 0.0 mm |
| US 6.5 | 256 mm | US 6 | 88% | +1.0 mm |
| US 7 | 263 mm | US 6.5 | 65% | -3.0 mm |
| US 7.5 | 266 mm | US 7 | 88% | +1.0 mm |
| US 8 | 269 mm | US 7.5 | 88% | +1.0 mm |
| US 8.5 | 273 mm | US 8 | 100% | 0.0 mm |
| US 9 | 276 mm | US 8.5 | 88% | +1.0 mm |
| US 9.5 | 279 mm | US 9 | 88% | +1.0 mm |
| US 10 | 283 mm | US 9.5 | 100% | 0.0 mm |
| US 10.5 | 286 mm | US 10 | 88% | +1.0 mm |
| US 11 | 289 mm | US 10.5 | 88% | +1.0 mm |
| US 11.5 | 293 mm | US 11 | 100% | 0.0 mm |
| US 12 | 296 mm | US 11.5 | 88% | +1.0 mm |
| US 12.5 | 299 mm | US 12 | 88% | +1.0 mm |
| US 13 | 303 mm | US 12.5 | 100% | 0.0 mm |
| US 14 | 309 mm | US 13 | 76% | -2.0 mm |
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Frequently Asked Questions
How does the Wool Runner size compare to the Cohesion 17?
The Cohesion 17 provides about 4mm more internal length than the Wool Runner. We suggest ordering 1/2 size down in Cohesion 17. The Wool Runner has an internal fit offset of -4mm compared to 0mm for the Cohesion 17.
Do these shoes fit wide feet comfortably?
The Wool Runner has a standard medium width profile, while the Cohesion 17 is standard medium.