At first, you can use ANY yarn you want. Fingering, DK, chunky …. anything :-)

A quick knit? Something easy but not too boring? Here it comes! Every row is the same - and both sides are looking identical.
1 - 2 - 3 - it doesn’t need more counting.
The cowl will be around 24 cm wide and as long as your head circumference + 5 cm (or as long as you want).

Because you can use any yarn and needle and only have to adjust the number of stitches it is difficult to say exactly how much yarn you will need.
My testers and I used used between 50 and 100 g - around 100 -250 meters. Except for the chunky yarn, there it was only 55 meters.

gauge:
16 sts = 10 cm (4“) for the pink version, 80 g needed
(handspun yarn, 50 g / 105 m, needle 5 mm / US 7)
18,5 sts = 10 cm (4“) for the rainbow version, 50 g needed
(Lang yarns Novena color, 50 g / 220 m, needle 5 mm / US 7)
9 sts = 10 cm (4“) for the blue version, 55 g needed
(creative melange super chunky, 100 g/100 m, needle 8 mm/US11)
Gauge for row is not important.