Crochet hook sizes matter. New crocheters may not notice a difference until they stare at a yarn aisle and see all the different sizes.
I recommend hook sizes when making a purchase for the first time. Look for 5 mm, 5.5 mm, 6 mm, or 6.5 mm. For our USA friends, that size is H, I, J, and K. Be careful with the Boye brand of hooks. See note below in the list.
If you are unsure, look at the ball band, which recommends the hook size needed.
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Sizes are indicated in the following order. Metric, USA, UK
- 2 mm, n/a, 14
- 2.25 mm, B/1, 13
- 2.50 mm, n/a, 12
- 2.75 mm, C, 11
- 3.00 mm, n/a, 11
- 3.25 mm, D, 10
- 3.50 mm, E/4, 9
- 3.75 mm, F, n/a
- 4.00 mm, 6, 8
- 4.25 mm, G, n/a
- 4.50 mm, 7, 7
- 5.00 mm, H/8, 6
- Careful Boye Hooks have 5.25 mm and are indicated as I/9 size. It’s not a standard size. Check the millimetres on the hook if required.
- 5.50 mm, I/9, 5
- 6.00 mm, J/10, 4
- 6.50 mm, K/10.5, 3
- 7.00 mm, n/a, 2
- 8.00 mm, L, 0
- 9.00 mm, M/N/15, 00
- 10.00 mm, P, 000
- 16.00 mm, Q, n/a
- 19.00 mm, S, n/a
- 25.00 mm, U, n/a
- 30.00 mm, Z, n/a
For beginners, I recommend the hook sizes in red for learning.
How to Check Gauge
Karen says
Hi, thank you for sharing your knowledge!! Have you done a percentage analysis yet? Like if using a size 4 yarn and changing hook size minimum to maximum, to see how the size changes. So a 4mm hook gets 2" X2" but a 5mm hook gets 2.25 x2.25" or whatever. I guess stitch used changes size too, so there's that.