Yarn Weight Converter
Identifying yarn weight correctly is essential for choosing the right needles, predicting gauge, and substituting yarns between patterns. The Craft Yarn Council uses a numeric system from 0 (lace) to 7 (jumbo) to categorise yarn weight universally across brand names and country conventions. Each category corresponds to a range of recommended US and metric needle sizes and a typical stitch gauge per 4 inches. The quickest way to identify an unlabelled yarn's weight is to measure its WPI (wraps per inch): wrap the yarn snugly around a ruler for exactly one inch without overlapping and count the wraps. Fewer wraps mean thicker yarn. Enter your WPI count below to see which weight category your yarn belongs to, along with recommended needle sizes, typical gauge, and common project types. You can also browse the complete Craft Yarn Council reference table to compare categories side by side. This tool is useful when working with destash yarn, inherited skeins, or hand-spun yarn where the original label is missing.
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Complete yarn weight reference table
Source: Craft Yarn Council standard yarn weight system. Gauge ranges assume stockinette stitch, blocked, on recommended needle size.
| # | Category name | WPI | US needles | Metric (mm) | Gauge (sts/4 in) | Typical uses |
|---|---|---|---|---|---|---|
| 0 | Lace / Thread | 30+ | 000-1 | 1.5-2.25 | 32-42 | Lace, doilies, thread crochet |
| 1 | Super Fine / Fingering | 14-30 | 1-3 | 2.25-3.25 | 27-32 | Socks, baby items, shawls |
| 2 | Fine / Sport | 12-18 | 3-5 | 3.25-3.75 | 23-26 | Baby garments, light sweaters |
| 3 | Light / DK | 11-15 | 5-7 | 3.75-4.5 | 21-24 | Light sweaters, shawls, hats |
| 4 | Medium / Worsted | 9-12 | 7-9 | 4.5-5.5 | 16-20 | Sweaters, blankets, scarves |
| 5 | Bulky / Chunky | 6-9 | 9-11 | 5.5-8 | 12-15 | Quick knits, rugs, winter wear |
| 6 | Super Bulky | 5-6 | 11-17 | 8-12.75 | 7-11 | Super chunky blankets, scarves |
| 7 | Jumbo / Roving | 1-4 | 17+ | 12.75+ | 6 or fewer | Extreme knitting, arm knitting |
How to measure WPI
- Cut a piece of your yarn approximately 12 inches long.
- Place a ruler flat on a table.
- Wrap the yarn snugly around the ruler at normal tension for exactly 1 inch. Wraps should be side by side, touching but not overlapping or bunching.
- Count the number of wraps within the 1-inch span.
- Enter that number in the WPI field above to see your yarn's weight category.
For plied yarns, measuring the full plied strand (not individual plies) gives the most accurate result.
Yarn weight: frequently asked questions
What is WPI (wraps per inch)?
WPI stands for wraps per inch. It is a simple way to measure yarn weight by wrapping yarn around a ruler or dowel for one inch and counting how many wraps fit side by side without overlapping or compressing. More wraps per inch means finer yarn. Fewer wraps per inch means thicker, bulkier yarn. WPI provides a quick way to identify the weight category of an unlabelled yarn.
How do I measure WPI accurately?
Hold the yarn at normal tension (not stretched, not slack) and wrap it around a ruler or cylindrical object for exactly one inch. Wraps should sit neatly side by side touching but not overlapping and not leaving gaps. Count the number of wraps. Measure twice for consistency. Plied yarns (two or more strands twisted together) give a more accurate reading than single-ply yarns which may squish together.
What is the difference between DK and worsted weight?
DK (double knitting) is a Light weight yarn, category 3 in the Craft Yarn Council system, typically yielding 21 to 24 stitches per 4 inches on size 5-7 US needles. Worsted is a Medium weight yarn, category 4, typically yielding 16 to 20 stitches per 4 inches on size 7-9 US needles. Worsted is thicker and knits up faster; DK produces a lighter, finer fabric.
Can I substitute one yarn weight for another?
Substituting a different weight yarn requires adjusting needle size and stitch count. Going up one category (e.g. sport to DK) produces a larger, looser fabric; going down produces a smaller, tighter one. For garments, swatching and recalculating stitch counts using the knitting gauge calculator is essential. Some pattern adjustments are complex; consider using a pattern designed for your available yarn weight.
Why does the same yarn label say different things in different countries?
Yarn weight naming conventions vary by country and manufacturer. A UK double knitting (DK) yarn is roughly equivalent to a US DK but UK ply naming also exists (4-ply, 8-ply, etc.) based on the number of strands. The Craft Yarn Council numeric system (0-7) is a standardised universal reference that cuts through these naming differences. WPI measurement is the most objective method for comparing yarns across countries.
Sources and methodology
- Craft Yarn Council yarn weight standards: CYC Yarn Weight.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. Gauge ranges are typical values; actual gauge depends on yarn, needles, and individual knitter tension. See our methodology.