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Crochet Hook Size Chart

Every common crochet hook in millimetres, US letters and old UK numbers, with the yarn weights each one suits. Pick a size in any system to convert it.

Hook size converter

5 mm

US H-8 · UK 6

Suits 3 Light (DK) yarn.

Crochet hook sizes: mm, US and UK

The yarn weight column shows the yarn weight categories each hook is usually paired with. Where a hook sits at the end of one range and the start of the next, both are shown.

MetricUSUK (old)Yarn weight
2.25 mmB-1130 Lace, 1 Super Fine
2.5 mm—121 Super Fine
2.75 mmC-2121 Super Fine
3.125 mmD—1 Super Fine
3.25 mmD-3101 Super Fine
3.5 mmE-491 Super Fine, 2 Fine
3.75 mmF-592 Fine
4 mmG-682 Fine
4.25 mmG—2 Fine
4.5 mm772 Fine, 3 Light
5 mmH-863 Light
5.25 mmI—3 Light
5.5 mmI-953 Light, 4 Medium
5.75 mmJ—4 Medium
6 mmJ-1044 Medium
6.5 mmK-10½34 Medium, 5 Bulky
7 mm—25 Bulky
8 mmL-1105 Bulky
9 mmM/N-13005 Bulky, 6 Super Bulky
10 mmN/P-150006 Super Bulky
11.5 mmP-16—6 Super Bulky
12 mm——6 Super Bulky
15 mmP/Q—6 Super Bulky, 7 Jumbo
15.75 mmQ—7 Jumbo
16 mmQ—7 Jumbo
19 mmS—7 Jumbo
25 mmT/U/X—7 Jumbo
30 mmT/X—7 Jumbo

Metric and US sizes from the Craft Yarn Council hook and needle standards; yarn weights from its Standard Yarn Weight System, which calls them guidelines. Old UK numbers aren't part of the standard: they're the usual equivalents and approximate. Some brands make the in-between sizes (3.125, 4.25, 5.25, 5.75 mm) and label them differently.

How to read a hook size

The millimetre size is the one to trust. It measures the diameter of the shaft, the part that sets the size of your loops, and it's printed on almost every hook made today. US hooks add a letter and number (a 5 mm hook is an H-8), but brands don't always agree on the letters, especially above 10 mm. Old UK numbers run backwards, so the bigger the number, the smaller the hook: a UK 8 is 4 mm and a UK 4 is 6 mm. You'll mostly meet them in vintage patterns.

Steel hooks for crochet thread have their own scale, which also runs backwards: steel 6, 7 and 8 are about 1.4–1.6 mm, used with lace weight yarn and fine cotton thread.

Choosing the right hook

Start with the hook on your yarn label or pattern, crochet a gauge swatch, and measure it. Too many stitches per 4 in (10 cm)? Go up a hook size. Too few? Go down. Changing hook is the normal way to match gauge, so don't worry if you end up a size or two away from the pattern. For a looser, drapier fabric, such as a shawl, go up a size; for firm amigurumi, go down one or two so the stuffing doesn't show.

FAQs

What size crochet hook is best for beginners?

A 5 mm (US H-8) or 5.5 mm (I-9) hook with smooth, light-coloured worsted or DK yarn. The stitches are big enough to see and count, and it's the size most beginner patterns use.

What is an H hook in mm?

An H-8 hook is 5 mm. A G-6 is 4 mm, an I-9 is 5.5 mm, a J-10 is 6 mm and a K-10½ is 6.5 mm.

Are crochet hooks and knitting needles sized the same way?

In millimetres, yes: a 4 mm hook and a 4 mm needle have the same diameter. The US numbers differ, though (a 4 mm needle is a US 6, a 4 mm hook is a G-6), so compare the millimetre sizes.

What does the UK size on an old pattern mean?

It's the old imperial gauge, used in Britain before metric sizes. Find it in the UK column above and use the metric hook next to it. Where two metric sizes share a number (UK 9 is listed for both 3.5 and 3.75 mm), make a swatch to decide.

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