Don't guess. Use this calculator to compare yarn weights and determine the exact adjustments for your knitting pattern.
Select original and substitute weights to get instant compatibility analysis.
Green = best match, Yellow = possible with adjustments, Red = not recommended.
| Original Weight | Best Substitutes | Possible Substitutes | Not Recommended |
|---|---|---|---|
| Lace (0) | Lace | Super Fine (1) | Fine (2) and heavier |
| Super Fine (1) | Super Fine | Lace (0), Fine (2) | Light (3) and heavier |
| Fine (2) | Fine | Super Fine (1), Light (3) | Lace (0), Medium (4)+ |
| Light / DK (3) | Light / DK | Fine (2), Medium (4) | Super Fine (1)−, Bulky (5)+ |
| Medium (4) | Medium / Worsted | Light (3), Bulky (5) | Fine (2)−, Super Bulky (6) |
| Bulky (5) | Bulky | Medium (4), Super Bulky (6) | Light (3) and lighter |
| Super Bulky (6) | Super Bulky | Bulky (5) | Medium (4) and lighter |
Finding the perfect yarn substitute is one of the most stressful parts of knitting. Whether the yarn listed in the pattern is discontinued, out of your budget, or uses an animal fiber you are allergic to, swapping it out without doing the math usually ends in disaster. This calculator analyzes the gap between your desired yarn and the original yarn, instantly predicting how your finished garment's drape, gauge, and structural integrity will be affected.
The Original Pattern Yarn: Look at the pattern requirements to identify the standard yarn weight requested (e.g., DK, Worsted, Fingering).
Your Stash / Chosen Yarn: Identify the standard weight of the yarn you want to use instead.
Use the first dropdown to select the yarn weight exactly as it is written in your pattern instructions.
Use the second dropdown to select the weight of the alternative yarn you have on hand.
Click "Analyze" to see if the swap is viable, complete with needle size adjustment tips and structural warnings.
If the result displays a green "Perfect Match", you can proceed normally (though you must still knit a gauge swatch). If it shows a yellow "Close Substitute", follow the specific needle adjustment advice (e.g., going down one needle size) and expect a slightly different drape. If you see a red "Not Recommended", stop immediately; the mathematical jump between the yarns is too severe and the pattern will warp beyond repair.
Scenario: You bought a beautiful sweater pattern that calls for Light / DK weight yarn, but you only have a stash of Medium / Worsted yarn.
Input: Original = Light (3) — DK. Substitute = Medium (4) — Worsted.
Conversion Math: The tool recognizes a one-step jump in thickness.
Result: Close Substitute (Yellow Flag). The tool advises you to go down 1 needle size. It warns that your fabric will be denser and slightly thicker than the designer intended.
Yes, but with immense caution. Wool is highly elastic and "remembers" its shape; cotton is completely inelastic and heavy. A large cotton sweater will droop under its own weight over time. If a pattern relies on negative ease (stretching to fit your body), cotton is usually a poor substitute for wool.
If you use DK instead of Worsted without changing needles, your stitches will be loose, airy, and "holy". If you go up a needle size to force the gauge, the fabric will become even floppier. This can look beautiful for a flowy summer shawl, but it will ruin a structured winter hat.
Absolutely. Heavier yarns yield fewer yards per 100 grams. If you are substituting a Worsted yarn into a DK pattern, you cannot just buy the same number of skeins. You must look at the total yardage required by the pattern, and buy enough skeins of your Worsted yarn to equal that total yardage.