Yarn Weight Conversion Chart: The Complete CYC 0-7 Reference Guide

Understanding the CYC yarn weight system

The Craft Yarn Council Standard Yarn Weight System standardised yarn classification in the early 2000s. Before this, "worsted" in the US, "10-ply" in Australia, and "Aran" in Britain could all describe roughly the same thickness — or three slightly different yarns, depending on the manufacturer. The CYC numbers 0-7 (with each yarn label also showing a small numbered yarn-ball icon) cut through that confusion. A label showing "4" is worsted-weight in any country, by any manufacturer.

The numbered system did not replace traditional names — most patterns still call for "DK weight" or "fingering" — but the CYC number provides an unambiguous reference. When a pattern's stated weight name confuses you, find the CYC number on the yarn label and match it. The number is the truth; the name is descriptive.

Complete yarn weight conversion chart (CYC 0-7)

CYC	Common names	WPI	Sc gauge / 4 in	Hook size	Typical projects
0	Lace, fingering, 10-count thread	30-40+	32-42	1.5-2.25 mm	Doilies, lace shawls, thread crochet
1	Super fine, fingering, sock, baby	14-30	21-32	2.25-3.5 mm	Socks, lacy garments, baby items
2	Fine, sport, baby	12-18	16-20	3.5-4.5 mm	Light garments, baby blankets
3	Light, DK, light worsted	11-15	12-17	4.5-5.5 mm	Cardigans, sweaters, blankets
4	Medium, worsted, afghan, Aran	9-12	11-14	5.5-6.5 mm	Most popular — afghans, hats, amigurumi
5	Bulky, chunky, craft, rug	6-9	8-11	6.5-9 mm	Quick blankets, scarves, winter accessories
6	Super bulky, super chunky, roving	5-7	7-9	9-15 mm	Chunky throws, statement scarves
7	Jumbo, roving	≤5	5-7	15+ mm	Arm-knitting, oversized rugs, statement pieces

For the corresponding crochet hook size chart in metric, US, and UK conventions, see the dedicated reference article.

Each yarn weight in detail

CYC #0 — Lace

The thinnest commercial yarn. Used almost exclusively for traditional doilies, fine lace shawls, and thread crochet. Worked with very small steel hooks (1.5-2.25 mm). Cotton in lace weight produces stiff structural lace; wool/silk blends produce drapey shawls. Most modern crocheters never use lace weight; it is a specialist material.

CYC #1 — Fingering / Sock

The standard yarn for socks. Fine enough that finished socks fit comfortably inside shoes. Also used for lacy garments where drape matters. Typical skein: 350-450 yards per 100 g. Brands: Patons Kroy Socks, Knit Picks Stroll, Drops Fabel.

CYC #2 — Sport / Baby

Slightly thicker than fingering. Common for baby garments and light summer wearables. Used to be more popular than it is today; many baby patterns have shifted to DK (#3) for slightly faster work-up. Typical skein: 250-350 yards per 100 g.

CYC #3 — DK (Double Knitting) / Light Worsted

The "Goldilocks zone" for many crocheters — fine enough for garments with drape, thick enough to work up quickly. DK is the standard for many cardigans, sweaters, and lightweight blankets. Typical skein: 230-280 yards per 100 g. Brands: Stylecraft Special DK, Drops Cotton Merino, Caron Simply Soft.

CYC #4 — Worsted / Aran

The most popular yarn weight in North America. Roughly half of all crochet patterns are written for worsted weight. Used for afghans, hats, mittens, amigurumi, and most general projects. Typical skein: 200-240 yards per 100 g. Brands: Red Heart Super Saver, Caron Simply Soft, Bernat Super Value.

CYC #5 — Bulky / Chunky

Twice as thick as worsted (roughly). Quick projects — a worsted scarf might take 8 hours; the same scarf in bulky takes 4. Bulky blankets are warm and finish fast. Typical skein: 130-170 yards per 100 g. Brands: Lion Brand Hometown USA, Bernat Softee Chunky.

CYC #6 — Super Bulky

Statement-piece yarn. Chunky throws, oversized scarves, dramatic winter accessories. Works up very fast — a queen blanket in super bulky can finish in a week of evenings versus 6+ weeks in worsted. Typical skein: 80-130 yards per 100 g.

CYC #7 — Jumbo

Roving-style yarn (often un-spun fleece). Used for arm-knitting/crocheting, where the "hook" is your arm. Trendy but specialist. One skein typically completes a small throw.

WPI (wraps per inch) — the universal thickness test

WPI measures how many strands of yarn wrap around a 1-inch ruler without overlapping or gapping. It is the most reliable way to verify a yarn's actual weight when the label is missing or you have unlabelled stash yarn. Wrap the yarn around a ruler with neutral tension (no stretching, no compressing) for one inch, count the wraps, and compare to the chart above. WPI is independent of fibre and brand — it measures the physical thickness directly.

To do the WPI test accurately: hold the ruler horizontally, wrap the yarn around it perpendicular to the long edge, count between two pin marks exactly 1 inch apart, repeat 3 times across the skein, and average the results. A 12 WPI yarn is in the #3 DK range; a 10 WPI yarn is in the #4 worsted range; a 7 WPI yarn is in the #5 bulky range.

International yarn weight names

The same physical yarn weight goes by different names in different countries. The CYC number on the label is the same everywhere; the descriptive names are not.

CYC	US / Canada	UK	Australia / NZ	Europe (Germany / France)
1	Fingering, sock	4-ply	4-ply	Sockenwolle / 4-fils
2	Sport, baby	5-ply	5-ply	Sport / Layette
3	DK, light worsted	DK	8-ply	DK
4	Worsted, Aran	Aran	10-ply	Worsted / Aran
5	Bulky, chunky	Chunky	12-ply	Dick / Épais
6	Super bulky	Super chunky	14-ply+	Sehr dick

Doubling up — combining yarn weights

Two strands of finer yarn held together can substitute for a thicker single strand. The general rule: two strands of CYC #1 fingering ≈ one strand of CYC #3 DK; two strands of CYC #3 DK ≈ one strand of CYC #5 bulky; three strands of CYC #1 ≈ one strand of CYC #4 worsted. Always swatch the doubled combination before committing — actual behaviour depends on the specific yarns' compressibility and twist.

Held-double crochet is common for adding contrasting colour without changing pattern (one strand of base colour, one strand of accent — produces a marled effect), for using up small leftover skeins, and for shifting a pattern's weight category without changing yarn.

Sources & further reading

• Craft Yarn Council — Standard Yarn Weight System
• Crochet Guild of America (CGOA) — professional standards
• Edie Eckman, The Crochet Answer Book (Storey Publishing) — technique reference
• Clara Parkes, The Knitter's Book of Yarn (Potter Craft) — fibre properties

Craft Yarn Council — Standard Yarn Weight System (official)

Ravelry — yarn weight system reference