Brooks to Triumph bra size

The short answer

Brooks L is Triumph 80C by the two brands' own charts.

Cups are counted along each brand's own letter order, and the band is carried across unchanged.

Every Brooks size read across to Triumph. Letter sizes on the left, EU on the right.
Brooks	Brooks builds it for	Triumph, by chart	Same label	Triumph builds it for	Triumph also prints
XS	not published	65B	not published	not published	UK B · US B · FR B · AU B
S	not published	70C	not published	not published	UK C · US C · FR C · AU C
M	not published	75C	not published	not published	UK C · US C · FR C · AU C
L	not published	80C	not published	not published	UK C · US C · FR C · AU C
XL	not published	85C	not published	not published	UK C · US C · FR C · AU C
XXL	not published	90C	not published	not published	UK C · US C · FR C · AU C

Tinted rows change label or sit between two sizes. 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

Brooks size guide, read on 2026-09-18. Brooks on TrueToSize
Triumph size guide, read on 2026-09-18.

Triumph to Brooks