True-to-Size Millimeter Sizing Comparison
Allbirds Wool Runner vs Nike Run Swift 3
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 Run Swift 3.
Complete Size Conversion Matrix
Direct millimeter-calibrated mapping comparing all available sizes between both shoes.
| Wool Runner (US) | Internal Cavity | Run Swift 3 Equivalent | Match Accuracy | Fit Difference |
|---|---|---|---|---|
| US 3.5 | 239 mm | US 6 | 98% | +0.2 mm |
| US 4 | 242 mm | US 6.5 | 74% | +2.2 mm |
| US 4.5 | 246 mm | US 7 | 74% | +2.2 mm |
| US 5 | 249 mm | US 7.5 | 62% | +3.2 mm |
| US 5.5 | 252 mm | US 7.5 | 98% | +0.2 mm |
| US 6 | 256 mm | US 8 | 98% | +0.2 mm |
| US 6.5 | 259 mm | US 8.5 | 86% | +1.2 mm |
| US 7 | 266 mm | US 9.5 | 62% | +3.2 mm |
| US 7.5 | 269 mm | US 9.5 | 98% | +0.2 mm |
| US 8 | 272 mm | US 10 | 86% | +1.2 mm |
| US 8.5 | 276 mm | US 10.5 | 86% | +1.2 mm |
| US 9 | 279 mm | US 11 | 62% | +3.2 mm |
| US 9.5 | 282 mm | US 11 | 98% | +0.2 mm |
| US 10 | 286 mm | US 11.5 | 98% | +0.2 mm |
| US 10.5 | 289 mm | US 12 | 86% | +1.2 mm |
| US 11 | 292 mm | US 12.5 | 74% | +2.2 mm |
| US 11.5 | 296 mm | US 13 | 74% | +2.2 mm |
| US 12 | 299 mm | US 13.5 | 50% | +4.2 mm |
| US 12.5 | 302 mm | US 13.5 | 86% | +1.2 mm |
| US 13 | 306 mm | US 14 | 86% | +1.2 mm |
| US 14 | 312 mm | US 15 | 62% | +3.2 mm |
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Frequently Asked Questions
How does the Wool Runner size compare to the Run Swift 3?
Both shoes share a very similar length profile. We recommend ordering your standard size in both. The Wool Runner has an internal fit offset of -0.68mm compared to -0.48mm for the Run Swift 3.
Do these shoes fit wide feet comfortably?
The Wool Runner has a standard medium width profile, while the Run Swift 3 is snug/narrow.