Brooks to On shoe size

The short answer

Brooks 11.5 is On 11 or 12 by the two brands' own charts. 2 of 16 Brooks sizes land on a different label at On.

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 Brooks size read across to On. US women's sizes on the left, US women's on the right.
Brooks	Brooks builds it for	On, by chart	Same label	On builds it for	On also prints
5	not published	5	not published	foot length 22 cm	UK 3 · EU 36 · CM / JP 22
5.5	not published	5.5	not published	foot length 22.5 cm	UK 3.5 · EU 36.5 · CM / JP 22.5
6	not published	6	not published	foot length 23 cm	UK 4 · EU 37 · CM / JP 23
6.5	not published	6.5	not published	foot length 23.5 cm	UK 4.5 · EU 37.5 · CM / JP 23.5
7	not published	7	not published	foot length 24 cm	UK 5 · EU 38 · CM / JP 24
7.5	not published	7.5	not published	foot length 24.5 cm	UK 5.5 · EU 38.5 · CM / JP 24.5
8	not published	8	not published	foot length 25 cm	UK 6 · EU 39 · CM / JP 25
8.5	not published	8.5	not published	foot length 25.5 cm	UK 6.5 · EU 40 · CM / JP 25.5
9	not published	9	not published	foot length 26 cm	UK 7 · EU 40.5 · CM / JP 26
9.5	not published	9.5	not published	foot length 26.5 cm	UK 7.5 · EU 41 · CM / JP 26.5
10	not published	10	not published	foot length 27 cm	UK 8 · EU 42 · CM / JP 27
10.5	not published	10.5	not published	foot length 27.5 cm	UK 8.5 · EU 42.5 · CM / JP 27.5
11	not published	11	not published	foot length 28 cm	UK 9 · EU 43 · CM / JP 28
11.5	not published	11 or 12	not published	foot length 28 cm	UK 9 · EU 43 · CM / JP 28
12	not published	12	not published	foot length 29 cm	UK 10 · EU 44 · CM / JP 29
12.5	not published	12	not published	foot length 29 cm	UK 10 · EU 44 · CM / JP 29
13	not published	not made	not published	not published	not published

Tinted rows change label or sit between two sizes. 1 sizes have no counterpart on the On 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.

Open in the converter Add an item you own

Sources

Brooks size guide, read on 2026-09-17. Brooks on TrueToSize
On size guide, read on 2026-09-17. On on TrueToSize

On to Brooks