by Alison Stapleton

Crochet Hook Sizes

Crochet hooks are measured in different sizes and the two types of measurement are metric and imperial.


Metric Size Hooks (UK)

Metric hook sizes are measured in millimeters (mm).

This refers to the diameter of the hook.

Such as:

1.25mm, 2mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 1mm, 15mm and 20mm.


Imperial Size Hooks (USA)

Imperial sizes are usually feet and inches and in this case crochet hooks are given a letter of the alphabet.

Crochet Hook Size Chart

Old US sizes


A 0 2.00 mm
B 1 2.25 mm
C 2 2.75 mm
D 3 3.25 mm
E 4 3.50 mm
F 5 3.75 mm
G 6 4.00 mm
7 4.50 mm
H 8 5.00 mm
I 9 5.5 mm
J 10 6 mm
K 10 ½ 6.5 mm
L 11 8 mm
M 13 9 mm
N / P 15 10 mm
O 12 mm
P / Q 15 mm
Q 16 mm
R 19 mm
S 25 mm

Hook materials

Crochet hooks can be made from many materials but the usual ones are:

  • Steel
  • Aluminium
  • Bamboo
  • Hardwood
  • Plastic
  • Glass

Bamboo and plastic crochet hooks bend and this can slow you down. The best hooks are made from steel, aluminum or hard woods like rosewood.

Aluminum crochet hooks come in different colors for each size so you can see immediately the difference between a 4.5mm hook and a 5mm hook.

Collecting hooks

Over time you will collect many crochet hooks in different sizes and also hooks in the same size so you can have one for each project or every place which you crochet.


For example I have one crochet hook in the kitchen drawer for squares and one in the car also for squares.

I also have a hook next to my chair in front of the TV for the bigger projects and blankets.