True-to-Size Millimeter Sizing Comparison

Allbirds Tree 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 Tree Runner
4.7(6,450 reviews)
Fit TendencyTrue to Size
Width ProfileStandard (Medium)
View Full Tree Runner Breakdown
Shoe Bwomen
On Cloud 6
4.0(384 reviews)
Fit TendencyTrue to Size
Width ProfileStandard (Medium)
View Full Cloud 6 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 Delta+0.27 mm

Interactive Size Converter

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

Recommended Size in On Cloud 6
EU 4265% Match

Internal shoe cavity difference: +3.0 mm (slightly roomier)

Alternate option if between sizes: EU 41 (53% match)

Complete Size Conversion Matrix

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

Tree Runner (US)Internal CavityCloud 6 EquivalentMatch AccuracyFit Difference
US 3.5240 mmEU 36100%0.0 mm
US 4243 mmEU 36.5100%0.0 mm
US 4.5247 mmEU 37100%0.0 mm
US 5250 mmEU 37.5100%0.0 mm
US 5.5253 mmEU 38100%0.0 mm
US 6257 mmEU 38.5100%0.0 mm
US 6.5260 mmEU 39100%0.0 mm
US 7267 mmEU 40100%0.0 mm
US 7.5270 mmEU 40.5100%0.0 mm
US 8273 mmEU 41100%0.0 mm
US 8.5277 mmEU 4265%+3.0 mm
US 9280 mmEU 42100%0.0 mm
US 9.5283 mmEU 42.5100%0.0 mm
US 10287 mmEU 43100%0.0 mm
US 10.5290 mmEU 4365%-3.0 mm
US 11293 mmEU 44100%0.0 mm
US 11.5297 mmEU 44.5100%0.0 mm
US 12300 mmEU 45100%0.0 mm
US 12.5303 mmEU 4565%-3.0 mm
US 13307 mmEU 46100%0.0 mm
US 14313 mmEU 47100%0.0 mm

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Frequently Asked Questions

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

Both shoes share a very similar length profile. We recommend ordering your standard size in both. The Tree Runner has an internal fit offset of -0.2mm compared to -0.2mm for the Cloud 6.

Do these shoes fit wide feet comfortably?

The Tree Runner has a snug/narrow width profile, while the Cloud 6 is roomy/wide.