Compare measured wraps per inch with overlapping yarn-weight guidance; verify the actual yarn label and swatch.
Compare measured wraps per inch with overlapping Craft Yarn Council yarn-category guidance.
Using the WPI reference
Compare measured wraps per inch with overlapping Craft Yarn Council yarn-category guidance.
Scope of this tool
WPI is an approximate thickness measurement. It does not identify fiber content, establish yardage per gram, or guarantee yarn substitution. Knitting gauge guidance uses stockinette; it is not a crochet gauge table.
Method and reference
WPI means the number of adjacent yarn wraps in one inch, without overlapping or stretching. The tool compares the entered value against the included guidance ranges and preserves multiple possible categories where ranges overlap.
What is this?
A reference that estimates possible yarn weight categories from your wraps-per-inch measurement, with recommended needles, hooks, gauge range, and project ideas.
Who needs it?
Fiber artists with unlabeled yarn who need to determine the weight category before starting a project.
Bottom line
Wrap your yarn around a ruler, count the wraps per inch, and enter the number to compare possible categories. Always check a swatch.
WPI to Yarn Weight Converter
How to Measure Wraps Per Inch
Yarn Weight Identification Results and Recommendations
Wrap your yarn around a ruler for one inch without stretching or overlapping. Count the wraps to find your WPI.
No measurement entered. No category result is shown.
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.
WPI Reference Chart
Weight
CYC
WPI
Needles
Hooks
Gauge
Yds/100g
Lace
0
30+
US 000–1
Steel 6–8; regular B/1
33–40 sts/4″
Use the yarn label
Super Fine
1
14–30
US 1–3
B/1–E/4
27–32 sts/4″
Use the yarn label
Fine / Sport
2
12–18
US 3–5
E/4–7
23–26 sts/4″
Use the yarn label
Light / DK
3
11–15
US 5–7
7–I/9
21–24 sts/4″
Use the yarn label
Medium / Worsted
4
9–12
US 7–9
I/9–K/10.5
16–20 sts/4″
Use the yarn label
Bulky
5
6–9
US 9–11
K/10.5–M/13
12–15 sts/4″
Use the yarn label
Super Bulky
6
5–6
US 11–17
M/13–Q
7–11 sts/4″
Use the yarn label
Jumbo
7
1–4
US 17+
Q+
6 and fewer sts/4″
Use the yarn label
WPI ranges overlap between adjacent weights. Swatching is the most reliable way to confirm yarn weight.
How to Measure WPI
Use a ruler or WPI tool. Wrap yarn snugly around it for exactly one inch.
Don't stretch the yarn. Let the wraps sit naturally side by side without gaps or overlapping.
Measure in multiple spots. Yarn thickness can vary along the skein, average 2–3 readings for accuracy.
Plied yarn can be tricky. Highly textured or bouclé yarns may not wrap evenly, swatch for the best results.
How to interpret WPI
WPI is subjective: wrap without stretching or leaving large gaps, measure several places, and compare the result with a swatch. CYC ranges overlap: Super Fine is 14–30, Fine is 12–18, Light is 11–15, Medium is 9–12, and Bulky is 6–9 WPI. An overlap returns every matching category; a gap returns none.
Needle and hook ranges are starting points. The listed gauge is knitting stockinette stitches per 4 inches, not crochet gauge. Use the actual pattern gauge and fabric you want to decide whether a yarn works.
Can WPI tell me how much yarn I have?
No. WPI does not establish yards per gram, fiber content, or care instructions. Use a yarn label or measure a known length and its mass. Confirm suitability with the actual yarn and pattern before starting.
How to use it
Measure the actual yarn without stretching it and enter the full measured value.
Review every matching category and verify the yarn with a representative swatch.
Read the result
WPI is an approximate thickness measurement. It does not identify fiber content, establish yardage per gram, or guarantee yarn substitution. Knitting gauge guidance uses stockinette; it is not a crochet gauge table.
Check before using the result
✓Follow the exact pattern and product instructions.
✓Make a representative swatch or sample when fit, dimensions, or material behavior matters.
Worked Example
A reading of 12 WPI falls in the included Fine, Light, and Medium guidance ranges. The overlap is a reason to check the label and swatch, not force a single category.