A few notes about casting on and circumference on this pattern:

The stated circumference is at the widest point of the cowl, but at certain parts, the circumference is smaller. The way the cowl is structured, you cast on, work for a bit, double your stitches, work for a bit, halve your stitches, work for a bit, double your stitches, work for a bit, halve your stitches again, work for a bit, and bind off. So, the majority of the cowl is the largest circumference, but it goes in and out. As it’s knitted at a loose gauge, the circumference is kind of dynamic - the wider parts pull the narrower parts out…

Also, as the pattern states, make sure to do your cast-on super loosely! If you’re having a hard time getting it loose, a Long-Tail CO instead of the Icord CO would be just fine.

Yarn: 375 yards worsted or aran-weight yarn. Sample shown in one skein of Blue Moon Fiber Arts LSS (50% merino wool, 50% silk; 500 yds per 226gr skein), colorway Spruced.
Gauge: 9 sts = 4 inches/10 cm over stockinette st.
Needles: US #11/8mm 24” or 32” circular needle or size to get gauge.
Notions: Stitch marker, tapestry needle.
Skill level: Advanced beginner.
Size/Finished measurements: One size fits most. 60” around, 16” tall.