What is the difference between DK and worsted weight yarn?

DK (double knitting) is CYC category 3 (light) with a knit gauge of 21–24 stitches per 4 inches, while worsted is CYC category 4 (medium) at 16–20 stitches per 4 inches. Worsted is thicker and knits up faster.

What does WPI stand for in yarn sizing?

WPI stands for 'wraps per inch'. To measure it, wrap yarn snugly (not tightly) around a ruler for one inch and count the wraps. More wraps indicate a finer yarn. Lace weight runs 30+ WPI; jumbo is 6 or fewer.

Is ply the same as yarn weight category?

No — ply refers to the number of twisted strands in a yarn, while weight category (CYC 0–7) describes overall thickness. A 4-ply yarn is typically fingering or sock weight, but different manufacturers use 'ply' inconsistently.

Can I substitute one yarn weight for another in a pattern?

Adjacent weight categories (e.g. DK for worsted) are sometimes substitutable by adjusting needle size, but your gauge swatch will change. Skipping two or more categories requires significant pattern modification.

What yarn weight is best for beginners?

Medium / worsted weight (CYC 4) is most beginner-friendly — it's easy to see stitches, works up quickly, and is available in every yarn store. Pair it with 4.5–5.5 mm needles or a 5 mm crochet hook.

Yarn Weight Converter — Lace to Jumbo, Ply & WPI Chart

Yarn Weight Chart

Yarn weight is the single most important specification when choosing yarn for a project. The Craft Yarn Council (CYC) defines 8 standard weight categories numbered 0 (lace) through 7 (jumbo), each with a recommended gauge range, wraps-per-inch (WPI) range, and suggested needle and hook sizes.

How it works

Each yarn label carries a CYC skein symbol (a numbered ball of yarn) alongside the recommended gauge and needle/hook size. The table above maps each category to:

CYC number and name — the standardized label
Ply count — number of twisted strands (not always consistent across manufacturers)
WPI — wraps per inch (measure by wrapping yarn snugly around a ruler for 1 inch)
Knit gauge — stitches per 4 inches / 10 cm in stockinette on recommended needles
Suggested needle and hook sizes — starting points for swatching

Practical examples

Example 1 — Identifying unmarked yarn. You have an unlabeled skein. Wrap it around a ruler; you count 16 wraps per inch. The WPI column shows 14–18 WPI corresponds to CYC 4 (Medium/Worsted). Start with a 5.0 mm needle.

Example 2 — Pattern calls for DK but you have fingering. DK is CYC 3 (21–24 stitches/4 in); fingering is CYC 1 (27–32 stitches/4 in). Two categories apart — expect significant gauge differences and likely pattern modifications.

Example 3 — Choosing yarn for a chunky hat. You want a quick knit. CYC 5 (Bulky, 12–15 stitches/4 in) on 5.5–8 mm needles will work up in a few hours; CYC 6 (Super Bulky) will be even faster but much thicker.

Common mistakes

Confusing ply with weight. A "4-ply" yarn is typically fingering/sock weight (CYC 1), not worsted. Ply count and weight category are independent properties.
Skipping the gauge swatch. The needle/hook sizes in the table are starting points. Your personal tension may require going up or down a size.
Mixing yarn weights in one project. Even small gauge differences create noticeable size inconsistencies. Always use the same yarn throughout a project.

International and regional variations

CYC Category	US Name	UK / Australian Name	Japanese Name
0	Lace	2-ply / Lace	レース糸 (lace thread)
1	Super Fine / Fingering	3-ply / 4-ply	合細 (gōbososo)
2	Fine / Sport	5-ply / Sport	中細 (chūbososo)
3	Light / DK	DK (double knitting)	合太 (gōbuto)
4	Medium / Worsted / Aran	Aran / Worsted	並太 (namibuto)
5	Bulky / Chunky	Chunky	極太 (gokubuto)
6	Super Bulky	Super Chunky	超極太 (chōgokubuto)
7	Jumbo	Jumbo	—

Quick reference

CYC #	Name	WPI	Knit gauge (4 in)	Needle (mm)
0	Lace	30+	33–40 sts	1.5–2.25
1	Super Fine	27–32	27–32 sts	2.25–3.25
2	Fine	23–26	23–26 sts	3.25–3.75
3	Light / DK	19–22	21–24 sts	3.75–4.5
4	Medium / Worsted	14–18	16–20 sts	4.5–5.5
5	Bulky	12–14	12–15 sts	5.5–8
6	Super Bulky	7–11	7–11 sts	8–12.75
7	Jumbo	1–6	6 or fewer sts	12.75+

For a complete side-by-side reference of US, metric, and UK needle and hook sizes with yarn weight recommendations, see the Knitting Needle & Crochet Hook Size Chart →.

Click a row to highlight it. Sizes vary by brand — use as a guide.

CYC #	Name	Ply	WPI	Knit gauge (4 in)	Needle (mm)	Hook (mm)
0	Lace	1–2	30+	33–40	1.5–2.25	1.5–2.25
1	Super Fine	3–4	27–32	27–32	2.25–3.25	2.25–3.5
2	Fine	5–6	23–26	23–26	3.25–3.75	3.5–4.5
3	Light	7–8	19–22	21–24	3.75–4.5	4.5–5
4	Medium	9–12	14–18	16–20	4.5–5.5	5–5.5
5	Bulky	13–14	12–14	12–15	5.5–8	5.5–6.5
6	Super Bulky	15+	7–11	7–11	8–12.75	6.5–9
7	Jumbo	—	1–6	6 or fewer	12.75+	9+

Frequently Asked Questions

What is the difference between DK and worsted weight yarn?: DK (double knitting) is CYC category 3 (light) with a knit gauge of 21–24 stitches per 4 inches, while worsted is CYC category 4 (medium) at 16–20 stitches per 4 inches. Worsted is thicker and knits up faster.
What does WPI stand for in yarn sizing?: WPI stands for 'wraps per inch'. To measure it, wrap yarn snugly (not tightly) around a ruler for one inch and count the wraps. More wraps indicate a finer yarn. Lace weight runs 30+ WPI; jumbo is 6 or fewer.
Is ply the same as yarn weight category?: No — ply refers to the number of twisted strands in a yarn, while weight category (CYC 0–7) describes overall thickness. A 4-ply yarn is typically fingering or sock weight, but different manufacturers use 'ply' inconsistently.
Can I substitute one yarn weight for another in a pattern?: Adjacent weight categories (e.g. DK for worsted) are sometimes substitutable by adjusting needle size, but your gauge swatch will change. Skipping two or more categories requires significant pattern modification.
What yarn weight is best for beginners?: Medium / worsted weight (CYC 4) is most beginner-friendly — it's easy to see stitches, works up quickly, and is available in every yarn store. Pair it with 4.5–5.5 mm needles or a 5 mm crochet hook.