True-to-Size Millimeter Sizing Comparison
Allbirds Wool Runner vs Nike Vomero 18
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 Vomero 18.
Complete Size Conversion Matrix
Direct millimeter-calibrated mapping comparing all available sizes between both shoes.
| Wool Runner (US) | Internal Cavity | Vomero 18 Equivalent | Match Accuracy | Fit Difference |
|---|---|---|---|---|
| US 3.5 | 236 mm | US 7 | 0% | +35.0 mm |
| US 4 | 239 mm | US 7 | 0% | +32.0 mm |
| US 4.5 | 243 mm | US 7 | 0% | +28.0 mm |
| US 5 | 246 mm | US 7 | 0% | +25.0 mm |
| US 5.5 | 249 mm | US 7 | 0% | +22.0 mm |
| US 6 | 253 mm | US 7 | 0% | +18.0 mm |
| US 6.5 | 256 mm | US 7 | 0% | +15.0 mm |
| US 7 | 263 mm | US 7 | 5% | +8.0 mm |
| US 7.5 | 266 mm | US 7 | 41% | +5.0 mm |
| US 8 | 269 mm | US 7 | 76% | +2.0 mm |
| US 8.5 | 273 mm | US 7.5 | 88% | +1.0 mm |
| US 9 | 276 mm | US 8 | 88% | +1.0 mm |
| US 9.5 | 279 mm | US 8 | 76% | -2.0 mm |
| US 10 | 283 mm | US 9 | 88% | +1.0 mm |
| US 10.5 | 286 mm | US 9.5 | 88% | +1.0 mm |
| US 11 | 289 mm | US 9.5 | 76% | -2.0 mm |
| US 11.5 | 293 mm | US 10.5 | 88% | +1.0 mm |
| US 12 | 296 mm | US 11 | 88% | +1.0 mm |
| US 12.5 | 299 mm | US 11 | 76% | -2.0 mm |
| US 13 | 303 mm | US 12 | 88% | +1.0 mm |
| US 14 | 309 mm | US 12.5 | 76% | -2.0 mm |
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Frequently Asked Questions
How does the Wool Runner size compare to the Vomero 18?
The Vomero 18 provides about 8mm more internal length than the Wool Runner. We suggest ordering 1 full size down in Vomero 18. The Wool Runner has an internal fit offset of -4mm compared to 4mm for the Vomero 18.
Do these shoes fit wide feet comfortably?
The Wool Runner has a standard medium width profile, while the Vomero 18 is standard medium.