Understand the best match between yarn weight and project

When we classify yarn by weight, it has little to do with how heavy a yarn is, but rather how thick the strand of the yarn is. The Craft Yarn Council, along with publishers, fiber and needle and hook manufacturers, have created a series of guidelines and symbols to bring uniformity to yarn, needle, and hook labeling to make it easier to select the right materials for a project and complete it successfully.

Yarn Substitution Guidelines

If your pattern calls for a specific yarn but you prefer to use a different yarn, you can use the yarn weights as a basis for substitution. While most yarns within a yarn weight category are interchangeable, not all are identical. It is imperative to construct a gauge swatch with the yarn that you intend to use in a project to be sure that you are matching the gauge of your project pattern.

Weight 0: Lace Weight

The lightest weight of yarn, producing an extremely fine gauge fabric. Lace weight yarns are often knit or crocheted on larger needles and hooks to create lacy, openwork patterns.

Best Uses: Delicate shawls, wraps, and intricate lacework

Recommended Knitting Needles: US 000–1 (1.5mm–2.25mm)
Recommended Crochet Hooks: Steel hooks 1.6mm–1.4mm or Regular 2.2mm

Common Gauge (over 4 inches):
Knitting Stockinette: 33–40 stitches | Crochet Single Crochet: 32–42 stitches

Note: Gauge is difficult to determine for lace weight yarns as it is often used to make lacy, open stitch work. Always follow the gauge as stated in your pattern.

Weight 1: Super Fine (Fingering or Sock)

More often referred to as fingering weight yarn, this is a bit heavier than lace and creates a more substantial fabric. Still very fine gauged, fingering weight yarn can also produce lovely openwork projects.

Best Uses: Socks, shawls, baby and adult garments, accessories

Recommended Knitting Needles: US 1–3 (2.25mm–3.25mm)
Recommended Crochet Hooks: B-1 to E-4 (2.25mm–3.5mm)

Common Gauge (over 4 inches):
Knitting Stockinette: 27–32 stitches | Crochet Single Crochet: 21–32 stitches

Weight 2: Fine Weight (Sport)

Often called sport or baby weight, this yarn is slightly heavier than fingering weight. Sport weight yarns are excellent for colorwork, textured fabric, and cabling.

Best Uses: Cozy socks, sweaters with great ease and drape, baby items

Recommended Knitting Needles: US 3–5 (3.25–3.75mm)
Recommended Crochet Hooks: E-4 to 7 (3.5mm–4.5mm)

Common Gauge (over 4 inches):
Knitting Stockinette: 23–26 stitches | Crochet Single Crochet: 16–20 stitches

Weight 3: Light Weight (DK / Double Knit)

More commonly called DK or Double Knit, this yarn creates a lovely, drapey fabric that is popular because it works up much faster than its thinner counterparts.

Best Uses: Sweaters, accessories, children's garments

Recommended Knitting Needles: US 5–7 (3.75mm–4.5mm)
Recommended Crochet Hooks: 7 to I-9 (4.5mm–5.5mm)

Common Gauge (over 4 inches):
Knitting Stockinette: 21–24 stitches | Crochet Single Crochet: 12–17 stitches

Weight 4: Medium Weight (Worsted and Aran)

More commonly known as worsted weight, this is the workhorse yarn of the knitting and crochet world. This yarn weight is very popular because it can be used for just about anything, bridging the gap between lighter and heavier weight yarns. Perfect for beginners of either craft.

Best Uses: Garments, accessories, home décor — virtually anything!

Recommended Knitting Needles: US 7–9 (4.5mm–5.5mm)
Recommended Crochet Hooks: I-9 to K-10½ (5.5mm–6.5mm)

Common Gauge (over 4 inches):
Knitting Stockinette: 16–20 stitches | Crochet Single Crochet: 11–14 stitches

Weight 5: Bulky Weight

Approximately twice as thick as worsted weight yarn. Sometimes referred to as chunky, craft, or rug yarn, it usually works up quickly using larger needles or hooks.

Best Uses: Heavy, cozy sweaters, rugs, throws

Recommended Knitting Needles: US 9–11 (5.5mm–8mm)
Recommended Crochet Hooks: K-10½ to M-13 (6.5mm–9mm)

Common Gauge (over 4 inches):
Knitting Stockinette: 12–15 stitches | Crochet Single Crochet: 8–11 stitches

Weight 6: Super Bulky

A very thick yarn that works up quickly on large needles and hooks.

Best Uses: Cowls, scarves, hats

Recommended Knitting Needles: US 11–17 (8mm–12.75mm)
Recommended Crochet Hooks: M-13 to Q (9mm–15mm)

Common Gauge (over 4 inches):
Knitting Stockinette: 7–11 stitches | Crochet Single Crochet: 7–9 stitches

Weight 7: Jumbo

The thickest yarn weight currently available. These super thick yarns are used in big stitch projects or for arm knitting or crochet.

Best Uses: Big stitch cowls, scarves, hats, blankets, arm knitting projects

Recommended Knitting Needles: US 17 and larger (15mm and larger)
Recommended Crochet Hooks: Q and larger (15mm and larger)

Common Gauge (over 4 inches):
Knitting Stockinette: 6 stitches and fewer | Crochet Single Crochet: 6 stitches and fewer