hook & needle sizes

Hook and needle size charts

Convert crochet hook and knitting needle sizes between metric, US and UK, and match them to yarn weights.

Crochet hook sizes

Metric	US	UK
2.25 mm	B-1	13
2.75 mm	C-2	11
3.25 mm	D-3	10
3.5 mm	E-4	9
3.75 mm	F-5	—
4 mm	G-6	8
4.5 mm	7	7
5 mm	H-8	6
5.5 mm	I-9	5
6 mm	J-10	4
6.5 mm	K-10½	3
8 mm	L-11	0
9 mm	M/N-13	00
10 mm	N/P-15	000

Knitting needle sizes

Metric	US	UK
2 mm	0	14
2.25 mm	1	13
2.75 mm	2	12
3.25 mm	3	10
3.5 mm	4	—
3.75 mm	5	9
4 mm	6	8
4.5 mm	7	7
5 mm	8	6
5.5 mm	9	5
6 mm	10	4
6.5 mm	10½	3
8 mm	11	0
9 mm	13	00
10 mm	15	000
12.75 mm	17	—
15 mm	19	—

Yarn weights and typical gauge (per 4 in / 10 cm)

Weight	Also called	Knit sts	Needles	Single crochet	Hook
1 · Super fine	Fingering, sock	27–32	2.25–3.25 mm	21–32	2.25–3.5 mm
2 · Fine	Sport, baby	23–26	3.25–3.75 mm	16–20	3.5–4.5 mm
3 · Light	DK, light worsted	21–24	3.75–4.5 mm	12–17	4.5–5.5 mm
4 · Medium	Worsted, aran	16–20	4.5–5.5 mm	11–14	5.5–6.5 mm
5 · Bulky	Chunky, craft	12–15	5.5–8 mm	8–11	6.5–9 mm
6 · Super bulky	Super chunky, roving	7–11	8–12.75 mm	7–9	9–15 mm
7 · Jumbo	Jumbo, roving	6 or fewer	12.75 mm +	6 or fewer	15 mm +

Good to know

Metric sizes are the most reliable, because US letters and UK numbers vary a little between brands. Yarn weights follow the Craft Yarn Council’s standard system; always check the recommendation on your yarn label.

Turn a photo into a pattern

What hook do I use for worsted yarn?

Usually 5.5–6.5 mm (US I-9 to K-10½) for crochet, and 4.5–5.5 mm (US 7–9) needles for knitting.

Why don’t UK and US sizes match?

They are separate numbering systems. The old UK system also runs backwards — bigger numbers are thinner.

More calculators

How much yarn do I need?

Enter the size of your project and your gauge to estimate yardage and skeins for single crochet, C2C, tapestry or stockinette.

Gauge calculator

Measure your swatch and find your gauge — then work out exactly how many stitches and rows you need for the size you want.

Blanket sizes, in stitches

Common blanket sizes with the stitches and rows — or C2C tiles — you need at your gauge.