Yarn Weight Calculator
Last updated: September 5, 2026
Estimate possible CYC yarn weight categories from wraps per inch (WPI) or knitting stockinette gauge. Covers all eight standard weights from Lace (0) through Jumbo (7).
A reference that estimates possible CYC yarn weight categories from your WPI count or knitting stockinette swatch measurement.
Any fiber artist working with unlabeled yarn, inherited stash, or yarn whose label has been lost.
Wrap yarn around a ruler, count wraps in one inch, enter the number, possible categories appear; swatch before choosing a yarn.
Wrap your yarn snugly around a ruler for one inch without stretching. Count the wraps and enter the number below.
Enter a finite measurement above 0 and at most 60; decimals are preserved. Blank or out-of-range measurements show no result. WPI is approximate, and gaps in the reference ranges are not assigned a category. Gauge ranges are for knitting in stockinette, not crochet. Always check a swatch. Sources: CYC WPI and CYC yarn weights.
No measurement entered. No category result is shown.
CYC Quick Reference
| # | Name | WPI | Gauge/4″ | Needles (US) |
|---|---|---|---|---|
| 0 | Lace | 30–Infinity | 33–40 | US 000–1 |
| 1 | Fingering | 14–30 | 27–32 | US 1–3 |
| 2 | Sport | 12–18 | 23–26 | US 3–5 |
| 3 | DK | 11–15 | 21–24 | US 5–7 |
| 4 | Worsted | 9–12 | 16–20 | US 7–9 |
| 5 | Bulky | 6–9 | 12–15 | US 9–11 |
| 6 | Super Bulky | 5–6 | 7–11 | US 11–17 |
| 7 | Jumbo | 1–4 | ≤6 | US 17+ |
How does the yarn weight calculator work?
Enter WPI or knitting stockinette stitches per 4 inches to compare with CYC ranges. WPI is subjective and overlapping categories all remain possible. Gauge mode uses knitting only: lace is 33–40 stockinette stitches per 4 inches. Measurements outside a listed range are not assigned a category. Neither method establishes the fiber content or guarantees substitution.
What yarn weight is best for a beginner project?
Start with the yarn and tools specified by a beginner pattern. Smooth yarn with visible stitches can make learning easier. No weight is universally best for every beginner or project; make a swatch before committing.
How do US yarn weights compare to UK and Australian terminology?
Regional names such as aran, worsted, DK, and ply labels are approximate comparisons, not a guarantee of identical thickness or gauge. Check the actual yarn label and pattern gauge. UK double crochet is US single crochet; confirm the pattern terminology before converting stitches.
What needle and hook size should I use for each yarn weight?
CYC needle and hook ranges are guidelines, not requirements. For lace, the chart lists 1.5–2.25 mm knitting needles, steel crochet hooks 1.4–1.6 mm, or a regular 2.25 mm hook. Brand letter and number sizes vary: check the marked millimetres and swatch to meet the pattern gauge.
How do I substitute one yarn weight for another?
A shared CYC category does not establish equivalent gauge, drape, or yardage per gram. Compare both labels and care instructions, then wash and measure a representative swatch in the pattern stitch. Different fibers and constructions can behave differently even within the same category.
Why does gauge matter when choosing a yarn weight?
Gauge determines the finished dimensions of your project. A half-stitch difference per inch becomes several inches of error across a full sweater or blanket. Two yarns in the same CYC category can produce different gauges depending on fiber, twist, and your personal tension.
Gauge is measured as the number of stitches (and rows) per 4 inches in the pattern's specified stitch. Each CYC category has a standard gauge range: Worsted (CYC 4) targets 16–20 stitches per 4 inches, DK (CYC 3) targets 21–24. If your swatch produces 22 stitches at 4 inches with a yarn labeled DK, but the pattern is written for 20 stitches at 4 inches in worsted, the unchanged stitch count models a width of 20 / 22 times the intended width. A nominal 20-inch width becomes about 18.18 inches, approximately 9.1% narrower. This says nothing about height; row gauge needs a separate comparison, enough to change the fit entirely.
Interweave and other major pattern publishers require a gauge swatch for every garment pattern precisely because yarn behavior varies this much between brands, fibers, and knitters. The Interweave guide to gauge explains how to measure accurately and adjust needle size when your swatch is off. For accessories like hats and mittens, even a one-stitch difference per inch can mean the difference between a snug fit and a too-loose piece.
Wash and block your swatch before measuring, some yarns (especially natural fibers like wool and cotton) relax significantly after washing. Superwash wool, for instance, can grow noticeably in both dimensions after the first wash. Measuring an unwashed swatch against a pattern designed for washed fabric can add another source of sizing error. Swatching completely, wash, dry, then measure, is the only reliable way to confirm gauge.
References and Industry Standards
- Craft Yarn Council, Yarn Weight System, Official CYC categories 0–7 with gauge and needle ranges
- Craft Yarn Council, Needle & Hook Size Chart, US, metric, and UK needle sizes by CYC category
- Ravelry, Yarn Weight Database, Browse yarn by CYC weight category across thousands of brands
- YarnSub, Free yarn substitution finder matching by weight, fiber, and yardage
- Interweave, How to Measure Knitting Gauge, Practical guide to swatching and gauge adjustment
Related Fiber Arts Tools
Yarn Weight & Substitution Guide
Interactive chart of all 8 CYC weights with US, UK, and Australian names
Gauge Calculator
Calculate measured gauge or proportionally scale an entered count, then review repeats, shaping, and fit separately
Yarn Yardage Calculator
Scale measured swatch use to a flat rectangular project
Needle & Hook Converter
Convert between US, metric, and UK needle and hook sizes
Frequently Asked Questions
- What yarn weight is right for a beginner project?
- Choose the yarn specified by a beginner pattern. CYC Medium (4), often called worsted or aran, has suggested knitting needles of 4.5–5.5 mm and crochet hooks of 5.5–6.5 mm; swatch to meet the pattern gauge.
- How do US CYC yarn weights compare to UK terminology?
- US worsted (CYC 4) is UK aran. US DK (CYC 3) is UK DK, one of the few consistent cross-market terms. US fingering (CYC 1) is UK 4-ply. US sport (CYC 2) is UK 5-ply or light DK. US bulky (CYC 5) is UK chunky. Note: US and UK crochet stitch names also differ, US single crochet equals UK double crochet.
- What needle or hook size pairs with each yarn weight?
- CYC 0 Lace: US 000–1 needle; steel 6–8 hook (1.4–1.6 mm) or regular B/1 (2.25 mm). CYC 1 Fingering: US 1–3, B/1–E/4 hook. CYC 2 Sport: US 3–5, E/4–7 hook. CYC 3 DK: US 5–7, 7–I/9 hook. CYC 4 Worsted: US 7–9, I/9–K/10.5 hook. CYC 5 Bulky: US 9–11, K/10.5–M/13 hook. CYC 6 Super Bulky: US 11–17, M/13–Q hook. CYC 7 Jumbo: US 17+, Q+ hook.
- How do I substitute one yarn weight for another?
- Matching categories do not guarantee interchangeable yarn. Compare the yarn labels, fiber and care, then swatch in the pattern stitch to check gauge, drape, and finished fabric. Category differences alone cannot prescribe a needle adjustment or yardage requirement.
- Why does gauge matter when choosing a yarn weight?
- Gauge determines the finished size of your project. Two yarns labeled the same CYC weight can produce different gauges depending on fiber, twist, and your individual tension. Always knit or crochet a gauge swatch before starting. Even a half-stitch difference per inch translates to several inches of error on a large project like a sweater or blanket.