True-to-Size Millimeter Sizing Comparison
Ryka Echo Knit Slip On vs Ryka Hydro Sport Water
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 Echo Knit Slip On to see your calculated size in the Hydro Sport Water.
Complete Size Conversion Matrix
Direct millimeter-calibrated mapping comparing all available sizes between both shoes.
| Echo Knit Slip On (US) | Internal Cavity | Hydro Sport Water Equivalent | Match Accuracy | Fit Difference |
|---|---|---|---|---|
| US 4.5 | 233 mm | US 3.5 | 20% | +6.8 mm |
| US 5 | 237 mm | US 3.5 | 67% | +2.8 mm |
| US 5.5 | 240 mm | US 3.5 | 98% | -0.2 mm |
| US 6 | 243 mm | US 4 | 98% | -0.2 mm |
| US 6.5 | 247 mm | US 4.5 | 98% | -0.2 mm |
| US 7 | 250 mm | US 5 | 98% | -0.2 mm |
| US 7.5 | 253 mm | US 5.5 | 98% | -0.2 mm |
| US 8 | 257 mm | US 6 | 98% | -0.2 mm |
| US 8.5 | 260 mm | US 6.5 | 98% | -0.2 mm |
| US 9 | 267 mm | US 7 | 98% | -0.2 mm |
| US 9.5 | 270 mm | US 7.5 | 98% | -0.2 mm |
| US 10 | 273 mm | US 8 | 98% | -0.2 mm |
| US 10.5 | 277 mm | US 8.5 | 98% | -0.2 mm |
| US 11 | 280 mm | US 9 | 98% | -0.2 mm |
Related Comparisons
ryka ComparisonDevotion X Walking vs Echo Knit Slip OnView Sizing Comparisonryka ComparisonDevotion X Max RS Walking vs Echo Knit Slip OnView Sizing Comparisonryka ComparisonDevotion X Walking vs Hydro Sport WaterView Sizing Comparisonryka ComparisonDevotion X Max RS Walking vs Hydro Sport WaterView Sizing Comparison
Frequently Asked Questions
How does the Echo Knit Slip On size compare to the Hydro Sport Water?
Both shoes share a very similar length profile. We recommend ordering your standard size in both. The Echo Knit Slip On has an internal fit offset of 0.2mm compared to 0mm for the Hydro Sport Water.
Do these shoes fit wide feet comfortably?
The Echo Knit Slip On has a roomy/wide width profile, while the Hydro Sport Water is roomy/wide.