Yarn Weight Chart: Categories 0 to 7 Explained for Crochet

Despite the name, yarn weight is about thickness, not how heavy a ball is. A 100 g ball of fine sock yarn and a 100 g ball of chunky yarn weigh the same, but the sock yarn is far thinner and much longer.

Thickness matters because it decides almost everything about a project: which hook to use, how big your stitches are, how the fabric drapes, how warm it is, and how much yarn you need.

To keep this consistent, the Craft Yarn Council created the Standard Yarn Weight System, which groups yarns into eight categories numbered 0 to 7, from the finest lace to the thickest jumbo yarn. Most yarn labels sold in the US show the number inside a small skein-shaped symbol.

These are the Craft Yarn Council's categories, with their recommended crochet hooks and typical crochet gauge, counted in single crochet over 4 inches (10 cm):

The CYC is clear that these are guidelines: the most common gauges and hook sizes for each category. Your pattern's gauge always comes first.

Our yarn weight converter shows each category with its hooks, gauges and typical uses side by side.

#0 Lace

Very fine yarn and crochet thread. Used for doilies, lace edgings, filet crochet and delicate shawls, usually with steel hooks. Slow to work up, but beautiful.

#1 Super fine

Sock, fingering and many baby yarns. Light and drapey, good for socks, lightweight shawls, baby garments and summer tops. Expect lots of stitches.

#2 Fine

Sport weight. A little thicker than fingering, great for baby blankets, light cardigans and detailed amigurumi.

#3 Light (DK)

DK ("double knitting") and light worsted. Very versatile: garments, baby items, hats and lighter blankets. Faster than fine yarns but still with good stitch definition.

#4 Medium

Worsted, afghan and aran. The most popular category, and the one most beginner patterns use. Ideal for blankets, hats, scarves, dishcloths (in cotton) and amigurumi. Aran tends to sit at the thicker end of this category.

#5 Bulky

Chunky yarn. Works up quickly into warm hats, cowls, quick blankets, baskets and rugs.

#6 Super bulky

Very thick yarn and roving. Makes cozy blankets in an evening or two, statement scarves and floor cushions.

#7 Jumbo

The thickest category, often used for giant-stitch blankets, pet beds and arm or hand crochet.

If you buy yarn or follow patterns from different countries, you'll meet different names for similar weights. UK, Australian and New Zealand patterns often use ply names:

Treat these as approximate matches. "Ply" originally meant the number of strands twisted together, but modern ply names describe overall thickness, and a "4-ply" yarn doesn't necessarily have four strands. Worsted and aran are often grouped together, but aran is usually a little thicker. When in doubt, compare the recommended gauge or hook size on the labels.

Found a mystery ball in your stash? The wraps per inch (WPI) test gives a good idea of its weight.

1. 1.Wrap the yarn around a ruler or pencil, laying each wrap snugly next to the last, without stretching the yarn or overlapping.
2. 2.Wrap enough to cover at least 1 inch, ideally 2.
3. 3.Count the wraps in 1 inch, or count over 2 inches and halve the result.
4. 4.Compare with the chart below.

WPI ranges overlap and vary between sources, because how tightly you wrap makes a difference. So use WPI to narrow it down, then make a small swatch with the suggested hook to confirm. If you can, compare against a labeled yarn you know.

A yarn label (also called a ball band) tells you nearly everything you need:

• Weight symbol: the CYC number from 0 to 7.
• Fiber content: wool, cotton, acrylic, blends. Fiber affects warmth, drape, stretch and care.
• Length and weight: for example, 200 yd (183 m) / 100 g. Use the length to work out how many balls you need.
• Recommended hook and gauge: a good starting point for swatching.
• Care instructions: washing, drying and ironing symbols, which also guide how you can block it.
• Color name and dye lot: buy all the yarn for a project from the same dye lot. Batches of the same color can differ slightly and show as stripes.

Keep one label from every project. If you need more yarn later, the dye lot number is the best chance of a match.

Can't find the yarn a pattern calls for? Substituting is easy if you follow a few rules.

1. 1.Match the weight category. Swap worsted for worsted, DK for DK.
2. 2.Check the gauge. Make a swatch with the new yarn and match the pattern's gauge, changing hooks if needed.
3. 3.Think about fiber. Cotton is heavier and less stretchy than wool; acrylic is lighter and easy to wash; wool is warm and springy. A cotton version of a wool hat pattern will be heavier and less stretchy.
4. 4.Buy by length, not by number of balls. Work out the total yardage the pattern needs, then divide by your new yarn's yards per ball.

Example: a pattern calls for 6 balls of a yarn with 220 yards each. That's 6 × 220 = 1,320 yards. Your substitute has 180 yards per ball: 1,320 ÷ 180 = 7.3, so buy 8 balls, or 9 to be safe.

Our skein calculator does this conversion for you, and the yarn calculator estimates total yardage for a project of any size.