Yarn amount used:
C1 purple: 7 g
C2 grey: 45 g
C3 white: 26 g

Needles:
Brim:
3.5 mm, 50 cm (Sandnes Garn)
Hat:
3.75 mm, 50 cm (Lykke interchangeables)
3.5 mm from rnd 52, magic loop.

Gauge in colorwork pattern, washed:
20.5 sts, 22 rows = 10 cm

My measurements: Circumference 47 cm (brim), 48 cm (hat body). Total length 28 cm. Brim length 2.5 cm. Body length 20 cm. Crown length 5.5 cm.

Next time, I might go down to a 3.5 mm needle for the colorwork.

My row gauge did grew more than in the sweater. The yarn used is merino superwash. Since I didn’t want to dry the hat flat from the beginning because I didn’t want a side fold (I did 1-2 hours later though), it might have grown even more than it would have otherwise. But the hat is nice and fits me well, a bit slouchy.

Yarn amount, details:
C1 purple:
(1) 35 g. 7 g used for brim, 28 g left.
C2 grey:
(1) 45 g, all used.
C3 white:
(1) 22 g - all used up at chart rnd 35.
(2) 49 g - 4 g used, 45 g left.