Birkenstock to Merrell shoe size

The short answer

Birkenstock 39 is Merrell 8 or 8.5 by the two brands' own charts.

At least one of the two brands publishes no foot length, so the rows line up the US size both charts print. Treat it as the label conversion, not a fit.

Every Birkenstock size read across to Merrell. EU sizes on the left, US women's on the right.
Birkenstock	Merrell, by chart	Same label	Merrell also prints
35	not made	not published	not published
36	5 or 5.5	not published	US men's 3.5 · UK 2.5 · EU 35 · CM / JP 22
37	6 or 6.5	not published	US men's 4.5 · UK 3.5 · EU 36 · CM / JP 23
38	7 or 7.5	not published	US men's 5.5 · UK 4.5 · EU 37.5 · CM / JP 24
39	8 or 8.5	not published	US men's 6.5 · UK 5.5 · EU 38.5 · CM / JP 25
40	9 or 9.5	not published	US men's 7.5 · UK 6.5 · EU 40 · CM / JP 26
41	10 or 10.5	not published	US men's 8.5 · UK 7.5 · EU 41 · CM / JP 27
42	11 or 11.5	not published	US men's 9.5 · UK 8.5 · EU 42.5 · CM / JP 28
43	not made	not published	not published
44	not made	not published	not published
48	not made	not published	not published

Neither chart publishes the body each size is built for, so the rows line up the labels. Tinted rows change label or sit between two sizes. 4 sizes have no counterpart on the Merrell chart. Read from the two charts only; no formula and no averaging.

What wearers say

Charts describe a garment. People who own both brands describe a fit, and their answer ranks above this table once five of them stand behind it. Pick your size in the converter to see whether there are enough yet.

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Sources

Birkenstock size guide, read on 2026-09-18.
Merrell size guide, read on 2026-09-18. Merrell on TrueToSize

Merrell to Birkenstock