True-to-Size Millimeter Sizing Comparison

KEEN Whisper vs Reef Fanning

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 Bunisex
Reef Fanning
4.6(3,385 reviews)
Fit TendencyTrue to Size
Width ProfileStandard (Medium)
View Full Fanning Breakdown
Fit Verdict

True to Size Comparison

Both shoes share a very similar length profile. We recommend ordering your standard size in both.

Length Delta0 mm
Width DeltaIdentical

Interactive Size Converter

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

Recommended Size in Reef Fanning
US 8.5100% Match

Internal shoe cavity difference: 0.0 mm (snugger)

Complete Size Conversion Matrix

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

Whisper (US)Internal CavityFanning EquivalentMatch AccuracyFit Difference
US 3.5240 mmUS 3.5100%0.0 mm
US 4243 mmUS 4100%0.0 mm
US 4.5247 mmUS 4.5100%0.0 mm
US 5250 mmUS 5100%0.0 mm
US 5.5253 mmUS 5.5100%0.0 mm
US 6257 mmUS 6100%0.0 mm
US 6.5260 mmUS 6.5100%0.0 mm
US 7267 mmUS 7100%0.0 mm
US 7.5270 mmUS 7.5100%0.0 mm
US 8273 mmUS 8100%0.0 mm
US 8.5277 mmUS 8.5100%0.0 mm
US 9280 mmUS 9100%0.0 mm
US 9.5283 mmUS 9.5100%0.0 mm
US 10287 mmUS 10100%0.0 mm
US 10.5290 mmUS 10.5100%0.0 mm
US 11293 mmUS 11100%0.0 mm
US 11.5297 mmUS 11.5100%0.0 mm
US 12300 mmUS 12100%0.0 mm
US 12.5303 mmUS 12.5100%0.0 mm
US 13307 mmUS 13100%0.0 mm
US 14313 mmUS 14100%0.0 mm

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Frequently Asked Questions

How does the Whisper size compare to the Fanning?

Both shoes share a very similar length profile. We recommend ordering your standard size in both. The Whisper has an internal fit offset of 0mm compared to 0mm for the Fanning.

Do these shoes fit wide feet comfortably?

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