Yarn and ball thickness guide (international standards)
Choosing the right yarn weight is key to the final result: the project’s texture, weight, and size. At Idealium, we follow the international CYC (0 to 7) classification and explain it in centimeters, with 10×10 cm gauges and needle and crochet hook ranges. Our goal: to help you choose confidently, without hesitation.
Table of contents
What “yarn weight” means
Yarn weight is the thickness of the yarn and determines how many stitches fit in a 10×10 cm swatch. The finer the yarn, the more stitches you’ll need; the thicker it is, the fewer stitches. For example, Fingering may be around 28–30 stitches/10 cm, while Bulky may be as low as 12–15 stitches/10 cm. In our yarn weight listings, you’ll see these references so you can compare at a glance.
International yarn weight chart (CYC 0–7)
Note: approximate ranges. The gauge is calculated in stockinette stitch using knitting needles. For crochet, with the same yarn weight, the gauge usually has fewer stitches.| CYC | Name | Knitting gauge (10 cm) | Knitting needles (mm) | Crochet gauge (10 cm) | Crochet hook (mm) | Recommended projects | ||
|---|---|---|---|---|---|---|---|---|
| 0 |
Lace Lace |
33–40 | 1,5–2,25 | 32–42 | 1,25–2,25 | Lace shawls, very lightweight garments | ||
| 1 |
Super Fine Fingering, Sock, 4 ply |
27–32 | 2,25–3,25 | 21–32 | 2,25–3,5 | Socks, lightweight tops, small amigurumi | ||
| 2 |
Fine Sport, 5 ply |
23–26 | 3,25–3,75 |
16–20 |
3,5–4,5 | Baby clothes, dense shawls, lightweight garments | ||
| 3 |
Light DK |
21–24 |
3,75–4,5 |
12–17 |
4,5–5,5 | Lightweight sweaters, cardigans, medium-sized amigurumi | ||
| 4 |
Medium Worsted / Aran* |
16–20 |
4,5–5,5 |
11–14 |
5,5–6,5 | Mid-season sweaters, blankets, accessories | ||
| 5 |
Bulky Chunky, 12-ply |
12–15 | 5,5–8 |
8–11 |
6,5–9 | Cowl necks, scarves, warm garments | ||
| 6 |
Super Bulky Super Chunky |
7–11 | 8–12,75 |
7–9 |
9–15 | XL blankets, baskets, chunky jackets | ||
| 7 |
Jumbo Arm knitting, roving |
≤6 | ≥12.75 | ≤6 | ≥15 | Pufs, rugs, XXL decor |
How to determine yarn weight if you don’t have a label
If you have a loose skein, you can estimate its category using a ruler in centimeters:
- Wrap the yarn without tightening it around a ruler or pencil for 2–3 cm.
- The rows should touch without overlapping.
- Count how many rows fit in 1 cm (or in 2 cm and divide by 2 for greater precision).
- Compare it with these approximate references:
| Yarn weight | Rows per cm (approx.) |
|---|---|
| Lace (0) | 7 or more |
| Fingering (1) | 5–6 |
| Sport (2) | ≈ 4.5 |
| DK (3) | ≈ 4 |
| Worsted / Aran (4) | ≈ 3.5 |
| Bulky (5) | ≈ 3 |
| Super Bulky (6) | ≈ 2 |
| Jumbo (7) | 1.5 or less |
Yarn weight equivalents that often cause confusion
- DK and Light Worsted are very similar; DK is just slightly finer. Check your swatch.
- Worsted and Aran share a category (CYC 4); Aran can be slightly thicker.
- “ply” (4-ply, 8-ply, etc.) is a historical UK/AUS term; today it is used as a reference for yarn weight, not the actual number of plies.
- In Europe, we use mm for needle and hook sizes. Always convert if your pattern uses the US/UK system.
- For crochet, the same yarn weight generally calls for slightly larger hooks than knitting needles.
How to adapt a pattern to a different yarn weight
- Compare your swatch. If the pattern calls for 20 stitches/10 cm and you get 18, knit or crochet more tightly, or go down 0.25–0.5 mm (if your project allows).
- Follow the measurements in centimeters. For garments, the final size (width, length, circumference, etc.) matters—not the number of rows.
- Choose “flexible” projects. Blankets, scarves, and hats are more forgiving of changes in yarn weight (adjust the width/length).
- For amigurumi, aim for a tight fabric. If the stuffing shows through, go down half a hook size or adjust your tension.
Frequently asked questions
Can I mix yarn weights? Yes, as long as the texture and final tension are consistent. For stripes or colorwork, try to use yarns that produce a similar swatch.
Does the fiber make a difference? A lot. Stretchy merino “fills out” more than cotton. That is why a swatch is your best ally.
Ideal yarn weight for beginners? DK (CYC 3) or Worsted/Aran (CYC 4): the stitches are easy to see and you work up projects quickly.
For amigurumi? Use a weight between Fingering and DK (CYC 1–3) with a slightly smaller crochet hook to close up the stitches.
T-shirt yarn and macramé cord? They are equivalent to Bulky–Jumbo (CYC 5–7); check the recommended needle/hook size and make a swatch.
Shop by yarn weight
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