Sun Hat Brim Shape + Support Planner

Turn your washed single-crochet gauge into a reachable crown count, a flat-annulus brim schedule and a support decision.

Brim profile
Measurement unit
Reachable crown count

Actual head circumferencein
Crown positive ease0–6%
Washed SC stitches countedstitches
Width of counted stitchesin
Washed SC rounds countedrounds
Height of counted roundsin
Crown center to brim joinin
Desired brim depthin
Washed stable overhangin
Planned edge supportafter washing test
Washed fabric light checkhold toward bright light

Geometry and support plan are workableThe selected count is reachable from the crown schedule, and the planned nylon cord matches this washed overhang result.

Selected crown/body count102 stitches22.67 in actual circumference

Flat brim16 rounds / 3.20 inends at 192 stitches

Support decisionUse nylon brim cordsupport ratio 1.16

Reach 102 stitches over 18 crown rounds, work about 16 even sidewall rounds to the measured wear depth, then work 16 brim rounds with 90 increases distributed around the fabric.

A dense handmade brim can create shade, but this calculator does not certify UPF. Pair the hat with sunscreen, sunglasses, clothing and shade.

Crown target circumference: 22.44 in
Raw stitch count: 100.98 stitches
Flat-circle increase rate q: 5.65 increases/round
Nearby reachable counts: 96 / 102 (nearest 102)
Actual crown ease: 3.0% positive
Approximate crown diameter: 7.22 in
Crown rounds: 18 rounds
Approximate even sidewall: 16 rounds
Finished outer diameter: 13.62 in
Broad-brim reference: At least 3 in; not UPF certification

Crown count path: 6, 12, 17, 23, 29, 34, 40, 46, 51, 57, 63, 68, 74, 80, 85, 91, 96, 102

Brim increases by round: +6, +5, +6, +6, +5, +6, +6, +5, +6, +6, +5, +6, +6, +5, +6, +5

Physical checkpoint wins: after Brim Rounds 4, 8 and 12, lay the hat flat without stretching. A ruffle means the increase rate is too high for the fabric; an upturned bowl means it is too low.