Weights & Gauge

Yarn weights and fabric weights, decoded.

"DK", "8-ply" and "category 3" all describe the same yarn. Here is how the naming systems line up, and what fabric weight numbers mean for cloth.

REF-01

Standard Yarn Weight System

The Craft Yarn Council's 0–7 categories, with typical stockinette gauge over 4 inches (10 cm) and recommended needle sizes.

#	Category	Common names	Sts / 4 in	Needle (mm)
0	Lace	Lace, cobweb, light fingering	33–40	1.5–2.25
1	Super Fine	Fingering, sock, baby	27–32	2.25–3.25
2	Fine	Sport, baby	23–26	3.25–3.75
3	Light	DK, light worsted	21–24	3.75–4.5
4	Medium	Worsted, aran, afghan	16–20	4.5–5.5
5	Bulky	Chunky, craft, rug	12–15	5.5–8
6	Super Bulky	Super bulky, roving	7–11	8–12.75
7	Jumbo	Jumbo, roving	≤ 6	12.75+

REF-02

"Ply" in UK and Australian naming describes thickness, not the actual number of strands. A modern 4-ply can be a single strand.

REF-03

For finished cloth, grams per square meter is the clearest single number for warmth and durability.

GSM	Typical fabric
120–200	Merino jersey, base layers
250–350	Shirting flannel, light suiting
350–450	Heavy flannel, jacket tweed
450–600	Coating, melton
600–750+	Mackinaw, heavy blanket cloth

Conversions: GSM = oz/yd² × 33.906. Suiting is often sold by weight per running meter, which depends on fabric width.

REF-04

Wraps per inch (WPI) — wrap the yarn snugly around a ruler without stretching and count. Higher WPI means thinner yarn.
Knit a swatch — at least 6 in square, washed and dried the way the finished piece will be. Measure the center 4 in.
Weigh and measure — yards per 100 g is the most reliable way to match a substitute yarn.