True-to-Size Millimeter Sizing Comparison

KEEN Whisper vs Reebok Classic Nylon

Detailed size conversion chart, cavity measurements in millimeters, and crowd-sourced fit advice for choosing your perfect size.

Shoe Aunisex
KEEN Whisper
5.0(4,157 reviews)
Fit TendencyTrue to Size
Width ProfileStandard (Medium)
View Full Whisper Breakdown
Shoe Bmen
Reebok Classic Nylon
5.0(7,279 reviews)
Fit TendencyRuns Small (-4mm)
Width ProfileStandard (Medium)
View Full Classic Nylon Breakdown
Fit Verdict

Classic Nylon Runs Slightly Smaller

The Classic Nylon is about 4mm shorter than the Whisper. We suggest ordering 1/2 size up in Classic Nylon.

Length Delta-4 mm
Width DeltaIdentical

Interactive Size Converter

Select what size you wear in the Whisper to see your calculated size in the Classic Nylon.

Recommended Size in Reebok Classic Nylon
US 988% Match

Internal shoe cavity difference: -1.0 mm (snugger)

Alternate option if between sizes: US 9.5 (76% match)

Complete Size Conversion Matrix

Direct millimeter-calibrated mapping comparing all available sizes between both shoes.

Whisper (US)Internal CavityClassic Nylon EquivalentMatch AccuracyFit Difference
US 3.5240 mmUS 70%+23.0 mm
US 4243 mmUS 70%+20.0 mm
US 4.5247 mmUS 70%+16.0 mm
US 5250 mmUS 70%+13.0 mm
US 5.5253 mmUS 70%+10.0 mm
US 6257 mmUS 729%+6.0 mm
US 6.5260 mmUS 765%+3.0 mm
US 7267 mmUS 7.588%-1.0 mm
US 7.5270 mmUS 888%-1.0 mm
US 8273 mmUS 8.5100%0.0 mm
US 8.5277 mmUS 988%-1.0 mm
US 9280 mmUS 9.588%-1.0 mm
US 9.5283 mmUS 10100%0.0 mm
US 10287 mmUS 10.588%-1.0 mm
US 10.5290 mmUS 1188%-1.0 mm
US 11293 mmUS 11.5100%0.0 mm
US 11.5297 mmUS 1288%-1.0 mm
US 12300 mmUS 12.588%-1.0 mm
US 12.5303 mmUS 13100%0.0 mm
US 13307 mmUS 1476%+2.0 mm
US 14313 mmUS 1453%-4.0 mm

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Frequently Asked Questions

How does the Whisper size compare to the Classic Nylon?

The Classic Nylon is about 4mm shorter than the Whisper. We suggest ordering 1/2 size up in Classic Nylon. The Whisper has an internal fit offset of 0mm compared to -4mm for the Classic Nylon.

Do these shoes fit wide feet comfortably?

The Whisper has a standard medium width profile, while the Classic Nylon is standard medium.