How to Choose Yarn Weight: The 0 to 7 Weights, Needle and Hook Sizes, and Best Projects

What do the yarn weight numbers mean?

The Craft Yarn Council Standard Yarn Weight System sorts yarn into eight categories. Each has a typical gauge range, the most commonly used needle and hook sizes, and a wraps per inch (WPI) range for identifying yarn without a label. These are guidelines drawn from the sizes knitters and crocheters most often use, so a pattern can call for something outside them.

Knit gauge is measured in stockinette and crochet gauge in single crochet, except lace, which the council gives in double crochet. Notice the overlaps: US 9 needles appear in both medium and bulky, which is why the yarn label and your own swatch matter more than the category alone. Each weight has a full profile, for example super fine yarn, medium yarn and super bulky yarn. For tool conversions, see the crochet hook size chart.

Which yarn weight should you use for which project?

Thinner yarn makes lighter, drapier, more detailed fabric and takes more stitches. Thicker yarn makes warm, sturdy fabric quickly but can look clumsy in fitted garments. The yardage ranges below are published planning estimates for knitting; they show how strongly weight changes the amount of yarn you buy.

Lace (0) and super fine (1) yarns are used mainly for shawls, doilies and socks, and jumbo (7) for arm-knit throws and pet beds, so general yardage tables rarely cover them. Yards per 100 g are retailer chart ranges, not a council standard, and fiber changes them a lot: cotton and wool of the same weight can differ by dozens of yards. Crochet usually takes about 25 to 33 percent more yarn than knitting for the same piece. Plan exact amounts with the yarn yardage calculator or see how much yarn for a throw blanket.

What yarn weight is best for beginners?

Medium (#4) worsted weight, in a smooth yarn and a light solid color. It is thick enough to see each stitch clearly, works on comfortable mid-size tools, and is sold everywhere in every fiber. Avoid black and navy, fuzzy mohair-style yarns, chenille and eyelash novelty yarns for a first project, because they hide stitches and make mistakes hard to find.

Three widely available examples show how labels guide you:

• Vanna's Choice: 100 g and 170 yd per skein of acrylic, with a knit gauge of 16 stitches and 22 rows on US 9.
• Basic Stitch Anti-Pilling: 100 g and 185 yd, 18 stitches and 26 rows on US 8, with an anti-pilling finish.
• Caron Simply Soft: 170 g and 315 yd, with a crochet gauge of 13 single crochet and 14 rows on a 5 mm (H/8) hook.

Pair a worsted yarn with US 8 (5 mm) needles or a 5 to 5.5 mm hook to start, then adjust after a swatch. Our best knitting needles for beginners roundup covers the first needles to buy.

What does DK mean in yarn weight?

DK stands for double knitting, the British name for light (#3) yarn, a little thinner than worsted. Yarn names come from different countries and eras, which is why one yarn can be called three things. Ply once described how many strands were twisted together, but modern yarn thickness no longer tracks ply count, so treat ply names as regional labels.

Aran deserves a note. The council groups it with worsted in medium (#4), but many brands and knitters treat aran as the heavier end of that range. When a pattern calls for aran, choose a yarn whose label gauge is near the lower stitch counts of medium, and swatch.

How do I know my yarn weight without a label?

Use wraps per inch. Wrap the yarn around a ruler or a pencil marked with an inch, laying each wrap snugly beside the last without stretching the yarn or overlapping. Count the wraps in one inch and compare with the WPI column above: 9 to 12 wraps suggests medium, 6 to 9 suggests bulky, 12 to 18 suggests fine. Because the ranges overlap, confirm with a swatch.

A second check is yards per 100 g. If you know or can measure the length of a ball, weigh it on a kitchen scale, then divide yards by grams and multiply by 100. A result of 170 to 230 points to medium; 300 to 380 points to fine. The yarn substitution calculator does both lookups and suggests a matching weight. Finally, knit a swatch on the needle size the result suggests and compare your stitches per 4 in with the gauge table. Our guide to measuring knitting gauge walks through it.

Can you hold two strands of yarn together to make a thicker weight?

Yes, and it is a handy way to use up stash or reach a weight you cannot find. A commonly cited rule of thumb is that two strands held together knit up roughly one to two weights heavier:

• Two strands of super fine (fingering) behave roughly like light (DK) or a light worsted.
• Two strands of light (DK) behave roughly like medium (worsted or aran).
• Two strands of medium (worsted) behave roughly like bulky (chunky).

The rule is only a starting point, because fiber, twist and loft change the result, so swatch before committing. One thing is certain: holding yarn double uses twice the yardage of each yarn, so a 200 yard hat in the combined weight needs 200 yards of each strand. Winding two balls into one double-stranded cake first on a winder such as the Stanwood metal winder and Amish swift, which handles 10 oz cakes, keeps the strands from twisting as you work.

Can I use a different yarn weight than the pattern calls for?

Only if you rework the numbers. A pattern's stitch counts are built on its gauge, so knitting a worsted pattern in bulky yarn with the same counts makes a much larger piece. For a hat written at 18 stitches per 4 in with 90 stitches around, the hat measures 20 in; the same 90 stitches at 13 per 4 in measure about 27.7 in.

The safe substitution is a yarn in the same weight category whose label gauge matches the pattern gauge, bought by yards, not grams. If you want to change weights on purpose, measure your new gauge and recalculate the stitch counts, or choose a pattern written for the weight you love. Plain blankets and scarves are the most forgiving places to experiment, since a slightly different size rarely matters. See the best yarn for blankets for weights that suit big projects.