Guides · Knitting & Crochet
Yarn weights, explained
Yarn weight has nothing to do with how heavy the ball feels in your hand. It is the thickness of the strand, sorted by the Craft Yarn Council into eight categories, 0 to 7, from thread fine lace to arm knitting jumbo. Learn the eight numbers and you can read any pattern, any yarn band, in any country, and you can swap one yarn for another without gambling a sweater on it.
Weight means thickness, and the number travels
The trap is built into the word. A 100 g ball of lace weight yarn and a 100 g ball of bulky yarn weigh the same on a scale, and they could not be less alike in the hand: the lace ball holds well over 800 metres of fine strand, the bulky ball perhaps 100 metres of thick one. Weight, in yarn language, is strand thickness, and the scale that sorts it is the Craft Yarn Council system, the small skein icon with a number that guide 06 showed you where to find on the band.
The number is the part that translates. The nicknames do not. DK is everyday language in the UK and a puzzle in the US. Worsted is everyday language in the US and means a spinning method, not a thickness, in the UK. Ply names in the UK and Australia, 4 ply, 8 ply, 10 ply, are thickness shorthand from the days when plies were a standard size, and a modern yarn can be built from any number of twisted plies at any thickness, so ply on a modern band tells you how the yarn is constructed, not how thick it is. Match the CYC number first, the gauge second, and the nickname last.
the number travels. the nicknames do not
The full table: CYC 0 to 7
| CYC | US name | UK and AU name | Knit gauge, sts | Crochet gauge, sts | Needles, mm | Hooks, mm |
|---|---|---|---|---|---|---|
| 0 | Lace | 1 to 3 ply | 33 to 40 | 32 to 42 | 1.5 to 2.25 mm | 1.6 to 2.25 mm |
| 1 | Super Fine, fingering and sock | 4 ply | 27 to 32 | 21 to 32 | 2.25 to 3.25 mm | 2.25 to 3.5 mm |
| 2 | Fine, sport | 5 ply | 23 to 26 | 16 to 20 | 3.25 to 3.75 mm | 3.5 to 4.5 mm |
| 3 | Light, DK | DK, 8 ply | 21 to 24 | 12 to 17 | 3.75 to 4.5 mm | 4.5 to 5.5 mm |
| 4 | Medium, worsted and aran | Aran, 10 ply | 16 to 20 | 11 to 14 | 4.5 to 5.5 mm | 5.5 to 6.5 mm |
| 5 | Bulky | Chunky, 12 ply | 12 to 15 | 8 to 11 | 5.5 to 8.0 mm | 6.5 to 9.0 mm |
| 6 | Super Bulky | Super chunky, 14 ply | 7 to 11 | 7 to 9 | 8.0 to 12.75 mm | 9.0 to 15.0 mm |
| 7 | Jumbo | Jumbo | 6 or fewer | 6 or fewer | 12.75 mm and up | 15.0 mm and up |
Read the table the way you will use it. The knit gauge is counted in stockinette, the crochet gauge in stitches over the same 4 in (10 cm), and both are ranges, not promises: two yarns can share a category and still sit at opposite ends of its gauge range, which is why the swatch in guide 02 has the final word. The tool columns are starting points in millimetres first, because mm is the only honest measure across the three sizing systems. A pattern that names its tool in US or old UK numbers only goes through the needle and hook size converter before it goes anywhere near yarn.
What each weight is actually for
Categories are not a ladder of skill, they are a trade between speed, drape and detail. Fine yarns buy detail and drape with time. Thick yarns buy speed and warmth with bulk. The short version, weight by weight:
| CYC | Works best for | The trade |
|---|---|---|
| 0 Lace | Lace shawls, fine scarves, heirloom work | The most detail and drape per gram, and the slowest going in the system. Blocking is the reveal, not the polish. |
| 1 Super Fine | Socks, shawls, baby clothes, light gloves | Fine fabric that wears hard in sock yarn. A garment here is a long, rewarding project. |
| 2 Fine | Baby blankets, light sweaters, sport weight garments | A step faster than fingering, a step lighter than DK, and often overlooked for exactly those reasons. |
| 3 Light, DK | Everyday sweaters, hats, baby and summer knits | The all rounder: stitch definition, moderate speed, garments that are neither heavy nor endless. |
| 4 Medium | First sweaters, dishcloths, amigurumi, afghans | The teaching weight. Big enough to read your stitches, fine enough to make real fabric. Most beginner patterns live here. |
| 5 Bulky | Fast hats, cowls, throws, warm scarves | Projects finish in evenings, and the fabric is warm and heavy. Yardage disappears faster than beginners expect. |
| 6 Super Bulky | Weekend blankets, chunky scarves, statement knits | Very fast and very warm. Garments can feel heavy to wear, and stitch mistakes show at poster size. |
| 7 Jumbo | Arm knit blankets, floor cushions, novelty throws | Worked with the biggest tools or your arms. Drape is not on the menu, impact is. |
One exception belongs in this section, because it breaks the table on purpose. Amigurumi makers work a weight 4 yarn on a hook one or two sizes smaller than the table suggests, so the fabric stays tight enough to hide the stuffing. Off table is a technique there, not an error, and the Amigurumi Starter Trio in the store is written that way.
No number on the band? Measure the strand yourself
Older yarns, indie yarns and mystery stash balls sometimes carry no CYC icon. Two checks place them, and together they are reliable.
- Metres per 100 g. Divide the ball's length by its gram weight and scale it to 100 g. As a rough sanity check only: lace runs about 800 m per 100 g and up, fingering about 360 to 460 m, sport about 250 to 350 m, DK about 200 to 250 m, worsted about 160 to 200 m, bulky about 100 to 160 m, super bulky about 50 to 100 m, and jumbo below that. Fibre and construction shift these numbers, cotton packs more metres of weight into less length than wool, so treat the result as a neighbourhood, not an address.
- Compare it against a yarn you know. Hold the mystery strand beside a ball whose category you trust, or wrap both, side by side and at the same snugness, around a ruler and count wraps per inch. The wraps count is only honest as a comparison between two yarns in your own hands, done the same way, and that comparison is exactly what a substitution needs.
Then swatch it. A yarn placed by both checks still earns a washed swatch before it earns a project, because its gauge on your tools is the number the pattern will actually meet.
A mystery ball reads 425 m and 100 g, no weight icon. Metres per 100 g puts it in the fingering neighbourhood, CYC 1. Wrapped beside a known sock yarn, the strands match. It is a fingering yarn until a swatch says otherwise, and patterns written for CYC 1, at 27 to 32 sts over 4 in (10 cm), are its hunting ground.
Safe substitutions: the four match rule
Substituting yarn is not shopping, it is engineering with soft materials. A swap is safe when four things match, and risky in proportion to how many of them you skip:
- Same CYC category. Start inside the pattern's weight number. One category out is a negotiation, two categories out is a different project wearing the pattern's name.
- Same gauge, on your swatch. Your washed and blocked swatch in the new yarn hits the pattern's stitches per 4 in (10 cm), changing tool size within the category's range if you need to. This is the match that decides fit, and no label can make it for you.
- Similar fibre and drape. Fibre is behaviour. Wool has spring and memory, cotton drapes and does not spring back, acrylic is light and holds the shape it was made in. A similar blend in the same category keeps the fabric's character. A different fibre family changes drape, weight in wear and care, even at a perfect gauge.
- Length, recalculated. Buy by the pattern's yardage, never by ball count or grams. Divide the pattern yardage by the new ball's yardage, round up, and add the spare ball for garments. A denser fibre gives fewer metres per 100 g, so matching grams is the classic way to run out at the second sleeve.
The traffic light version
| The swap | Call | Why |
|---|---|---|
| Same category, similar fibre, swatch on gauge | Safe | All four matches in place. This is substitution working as intended. |
| Same category, different fibre family | Swatch and think | Gauge can match while drape and wear change. Fine for blankets and dishcloths, a real decision for a fitted garment. |
| One category up or down, for a scarf, blanket or toy | Workable, recalculated | Nothing has to fit a body. Expect a bigger or smaller result, and recalculate length before you buy. |
| One category up or down, for a garment | Risky | Every measurement scales with the gauge change, and stitch patterns and shaping were written for the original fabric. |
| Two categories away, or no swatch at all | Stop | You are no longer substituting, you are redesigning without doing the design work. |
First Sweater, No Tears is written for CYC 4 worsted at 18 sts and 24 rows over 4 in (10 cm), 1,050 to 2,050 yd across its sizes. Another CYC 4 yarn in a wool or wool blend fibre, swatched to that gauge, is a safe swap, bought by length from the size table. The same sweater in a CYC 4 cotton is the amber call: gauge can match, but cotton is heavier in wear and does not spring back at cuffs and hems, so the sweater will drape and grow differently, and that is a choice to make on purpose, not discover in October.
The Dishcloth Course cloth is the forgiving end of the craft: about 75 yd of CYC 4 cotton for an 8 in (20 cm) cloth. Any CYC 4 cotton or cotton rich blend substitutes safely, because absorbency is the job and cotton is the fibre that does it. A CYC 4 acrylic keeps the size and loses the point, it does not absorb like cotton, which is the four match rule catching a swap that the gauge alone would have waved through.
Last, the stash question this guide exists to answer. When you hold a ball and ask what it could become, the honest order is: find its number, check its fibre, then go looking for patterns written at that number, and put your yardage into the yarn yardage calculator to see which project sizes your length actually covers. Weight first, wishes second. The stash rewards it every time.