True-to-Size Millimeter Sizing Comparison
Lucky Brand Basel vs Lucky Brand Eikia Ballet Flat
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 Basel to see your calculated size in the Eikia Ballet Flat.
Complete Size Conversion Matrix
Direct millimeter-calibrated mapping comparing all available sizes between both shoes.
| Basel (US) | Internal Cavity | Eikia Ballet Flat Equivalent | Match Accuracy | Fit Difference |
|---|---|---|---|---|
| US 4.5 | 232 mm | US 4.5 | 97% | -0.2 mm |
| US 5 | 236 mm | US 5 | 97% | -0.2 mm |
| US 5.5 | 239 mm | US 5.5 | 97% | -0.2 mm |
| US 6 | 242 mm | US 6 | 97% | -0.2 mm |
| US 6.5 | 246 mm | US 6.5 | 97% | -0.2 mm |
| US 7 | 249 mm | US 7 | 97% | -0.2 mm |
| US 7.5 | 252 mm | US 7.5 | 97% | -0.2 mm |
| US 8 | 256 mm | US 8 | 97% | -0.2 mm |
| US 8.5 | 259 mm | US 8.5 | 97% | -0.2 mm |
| US 9 | 266 mm | US 9 | 97% | -0.2 mm |
| US 9.5 | 269 mm | US 9.5 | 97% | -0.2 mm |
| US 10 | 272 mm | US 10 | 97% | -0.2 mm |
| US 10.5 | 276 mm | US 10.5 | 97% | -0.2 mm |
| US 11 | 279 mm | US 11 | 97% | -0.2 mm |
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Frequently Asked Questions
How does the Basel size compare to the Eikia Ballet Flat?
Both shoes share a very similar length profile. We recommend ordering your standard size in both. The Basel has an internal fit offset of -0.52mm compared to -0.76mm for the Eikia Ballet Flat.
Do these shoes fit wide feet comfortably?
The Basel has a snug/narrow width profile, while the Eikia Ballet Flat is snug/narrow.