As this hat is made with measurements, you can use any hook and any yarn you prefer.

However, the hook you use should be 2 sizes bigger than the hook you normally use with the yarn you choose. It has to be very loose.

I normally use the 5mm with Drops Nepal, but for this hat I used the 7mm

Tape Measurer

Calculator

I used for the hat in the picture:

Drops Nepal, Yarn thickness group C, 50 gr = 82 yds, 10wpi
With the 7mm hook: HDC 10x10cm (4”x4”) = 9st x 10 rows

After completing R3a (still in the increasing stage), the diameter of your work should measure 10 cm / 4 inches across, if you follow my gauge and calculations as mentioned below.

For the child size hat as pictured:

For the three color hat, use 1 skein of each color. You will not use all of it.

Yarn needle to weave in ends

Stitches used:

MC - Magic Circle
CH - Chain
SLST - Slip stitch
HDC - Half Double Crochet