Wraps Per Inch Calculator
Enter your WPI measurement to find your yarn weight category and recommended hook and needle sizes.
wraps per inch
Results are estimates. WPI can vary slightly based on how tightly or loosely you wrap the yarn.
WPI Reference Table
| WPI Range | Yarn Weight | CYCA # | Needle (mm) | Hook (mm) |
|---|---|---|---|---|
| 30+ | Lace / Cobweb | 0 | 1.5–2.25 | 1.75–2.25 |
| 20–30 | Cobweb / Fine Lace | 0 | 2.0–2.25 | 2.0–2.25 |
| 14–20 | Fingering / Sock | 1 | 2.25–3.25 | 2.25–3.5 |
| 12–14 | Sport / Baby | 2 | 3.25–3.75 | 3.5–4.5 |
| 11–12 | DK / Light Worsted | 3 | 3.75–4.5 | 4.5–5.5 |
| 9–10 | Worsted | 4 | 4.5–5.5 | 5.0–6.5 |
| 7–8 | Aran / Heavy Worsted | 4 | 5.0–5.5 | 5.5–6.5 |
| 5–6 | Bulky / Chunky | 5 | 5.5–8.0 | 6.5–9.0 |
| 4–5 | Super Bulky | 6 | 8.0–12.75 | 9.0–15.0 |
| 1–3 | Jumbo / Roving | 7 | 12.75+ | 15.0+ |
How to Measure WPI at Home
- Hold a ruler (or pencil/dowel) horizontally with one hand.
- Wrap the yarn snugly around the ruler, making sure each wrap sits neatly next to the previous one — no gaps, no overlapping.
- Wrap for exactly one inch (between the 1" and 2" marks, for example).
- Count the number of wraps in that one inch — that is your WPI.
- Wrap at a consistent tension: not too tight (which compresses wraps) and not too loose (which spreads them).
Tips
- If your yarn is very fuzzy (mohair, angora), smooth the fibers gently before measuring — the halo can inflate your count.
- WPI is most useful for unlabeled or handspun yarn. If you have a label, trust the label's weight classification.
- A yarn on the borderline between two WPI ranges may work for either weight — swatch to confirm.