Yarn and skein thickness guide (international standards)
Choosing the right yarn weight is key to the final result: the texture, weight, and size of your project. At Idealium, we follow the international CYC classification (0 to 7) and explain it in centimeters , with 10x10 cm samples and needle and crochet hook size ranges. Our goal: to help you choose with confidence, without any doubts.
What does the “thickness” of a thread mean?
The thickness refers to the thickness of the yarn and determines how many stitches fit into a 10x10 cm swatch. The thinner the yarn, the more stitches you'll need; the thicker the yarn, the fewer stitches. For example, a Fingering yarn might require around 28–30 stitches/10 cm , while a Bulky yarn might only require 12–15 stitches/10 cm . Our thickness charts provide these references so you can easily compare them.
International thickness chart (CYC 0–7)
Note: These are approximate ranges. The gauge is calculated using two-needle stockinette stitch. For the same yarn weight, crocheting will typically yield fewer stitches.| CYC | Name | Sample point (10cm) | Knitting needles (mm) | Crochet sample (10cm) | Crochet (mm) | Recommended projects | ||
|---|---|---|---|---|---|---|---|---|
| 0 |
Lace Lace |
33–40 | 1.5–2.25 | 32–42 | 1.25–2.25 | Lace shawls, very light garments | ||
| 1 |
Super Fine Fingering, Sock, 4 ply |
27–32 | 2.25–3.25 | 21–32 | 2.25–3.5 | Socks, thin tops, small amigurumi | ||
| 2 |
Fine Sport, 5 ply |
23–26 | 3.25–3.75 |
16–20 |
3.5–4.5 | Baby clothes, closed shawls, lightweight garments | ||
| 3 |
Light DK |
21–24 |
3.75–4.5 |
12–17 |
4.5–5.5 | Fine sweaters, jackets, medium-sized amigurumi | ||
| 4 |
Medium Worsted / Aran* |
16–20 |
4.5–5.5 |
11–14 |
5.5–6.5 | Transitional sweaters, blankets, accessories | ||
| 5 |
Bulky Chunky, 12-ply |
12–15 | 5.5–8 |
8–11 |
6.5–9 | Collars, scarves, warm clothing | ||
| 6 |
Super Bulky Super Chunky |
7–11 | 8–12.75 |
7–9 |
9–15 | XL blankets, baskets, thick jackets | ||
| 7 |
Jumbo Arm knitting, roving |
≤6 | ≥12.75 | ≤6 | ≥15 | Poufs, rugs, XXL decor |
How to tell the thickness if there's no label
If you have a loose ball of yarn, you can estimate its category using a ruler in centimeters :
- Loosely wrap the yarn around a ruler or pencil for 2–3 cm.
- The turns should touch , without overlapping.
- Count how many turns fit in 1 cm (or in 2 cm and divide by 2 for more precision).
- Compare it with these indicative references:
| Thickness | Turns 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 |
Equivalencies that often cause doubt
- DK and Light Worsted are very similar; DK is just slightly finer. Check the sample.
- Worsted and Aran share category (CYC 4); Aran may be a coarser point.
- “ply” (4-ply, 8-ply…) is a historical UK/AUS term; today it is used as a reference to thickness, not the actual number of strands.
- In Europe we use millimeters for needles/hooks. Always convert if your pattern is in US/UK size.
- In crochet , for the same thickness of yarn, crochet hooks that are slightly larger than knitting needles are used.
How to adapt a pattern to a different thickness
- Compare the gauge. If the pattern calls for 20 stitches/10 cm and you get 18, knit tighter or decrease by 0.25–0.5 mm (if your project allows it).
- Follow the measurements in centimeters. For garments, the important thing is the final size (width, length, circumference…), not the number of rounds.
- Choose "flexible" projects. Blankets, scarves, and hats tolerate changes in thickness better (adjust width/length).
- When crocheting amigurumi , aim for a tight, closed stitch. If the stuffing is showing, use a smaller crochet hook size or adjust the tension.
Frequently Asked Questions
Can I mix thicknesses? Yes, as long as the final texture and tension are consistent. In stripes or colorwork, try to use yarns that have a similar appearance.
Does the fiber matter? A lot. A stretchy merino wool feels fuller than cotton. That's why a sample is your best friend.
Ideal thickness to start with? DK (CYC 3) or Worsted/Aran (CYC 4) : the stitches are visible and you progress quickly.
For amigurumi? Between Fingering and DK (CYC 1–3) with a slightly smaller crochet hook to close the stitch.
T-shirt yarn and macrame cord? They are equivalent to Bulky–Jumbo (CYC 5–7) ; check the recommended needle/hook size and make a sample.
Buy by thickness
Choose your thickness and start today
