True-to-Size Millimeter Sizing Comparison

Allbirds Wool Runner vs On Cloud 6

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

Shoe Aunisex
Allbirds Wool Runner
4.6(3,196 reviews)
Fit TendencyRuns Small (-4mm)
Width ProfileStandard (Medium)
View Full Wool Runner Breakdown
Shoe Bwomen
On Cloud 6
4.0(377 reviews)
Fit TendencyTrue to Size
Width ProfileStandard (Medium)
View Full Cloud 6 Breakdown
Fit Verdict

Cloud 6 Runs Slightly Larger

The Cloud 6 provides about 4mm more internal length than the Wool Runner. We suggest ordering 1/2 size down in Cloud 6.

Length Delta+4 mm
Width DeltaIdentical

Interactive Size Converter

Select what size you wear in the Wool Runner to see your calculated size in the Cloud 6.

Recommended Size in On Cloud 6
US 10100% Match

Internal shoe cavity difference: 0.0 mm (snugger)

Complete Size Conversion Matrix

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

Wool Runner (US)Internal CavityCloud 6 EquivalentMatch AccuracyFit Difference
US 3.5236 mmUS 588%+1.0 mm
US 4239 mmUS 5.588%+1.0 mm
US 4.5243 mmUS 6100%0.0 mm
US 5246 mmUS 6.588%+1.0 mm
US 5.5249 mmUS 788%+1.0 mm
US 6253 mmUS 7.5100%0.0 mm
US 6.5256 mmUS 888%+1.0 mm
US 7263 mmUS 8.565%-3.0 mm
US 7.5266 mmUS 988%+1.0 mm
US 8269 mmUS 9.588%+1.0 mm
US 8.5273 mmUS 10100%0.0 mm
US 9276 mmUS 10.588%+1.0 mm
US 9.5279 mmUS 1188%+1.0 mm
US 10283 mmUS 1165%-3.0 mm
US 10.5286 mmUS 1129%-6.0 mm
US 11289 mmUS 110%-9.0 mm
US 11.5293 mmUS 110%-13.0 mm
US 12296 mmUS 110%-16.0 mm
US 12.5299 mmUS 110%-19.0 mm
US 13303 mmUS 110%-23.0 mm
US 14309 mmUS 110%-29.0 mm

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Frequently Asked Questions

How does the Wool Runner size compare to the Cloud 6?

The Cloud 6 provides about 4mm more internal length than the Wool Runner. We suggest ordering 1/2 size down in Cloud 6. The Wool Runner has an internal fit offset of -4mm compared to 0mm for the Cloud 6.

Do these shoes fit wide feet comfortably?

The Wool Runner has a standard medium width profile, while the Cloud 6 is standard medium.