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Yarn Substitution Calculator

Swap the yarn in any pattern: enter the yardage required and your substitute's yards per skein to find how many skeins to buy and your leftover.

Yardage the pattern needs

Substitute yarn — yards per skein

Grams per skein (optional)

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How it works

Skeins needed = ⌈yardage required ÷ yards per skein⌉ · Total yardage = skeins × yards per skein · Leftover = total − required

Patterns are honestly written in yardage (or metres), not in "3 balls of Brand X," because a substitute yarn almost never has the same length per skein. To swap safely, work in yardage: take the total the pattern requires, divide by your substitute's yards per skein, and round up — you can never buy a partial skein, and running out one dye lot short is a knitter's nightmare. The reason yards-per-skein varies so much is weight and fibre: a 100 g skein of fine fingering yarn holds far more length than a 100 g skein of chunky wool, so matching weight class matters as much as matching yardage. Always match the pattern's yarn weight (gauge) first, then buy enough yards, and buy it all together so every skein shares one dye lot.

Worked example

A sweater pattern needs 1,000 yd of worsted. Your chosen yarn comes in 220-yd skeins, so 1,000 ÷ 220 ≈ 4.55, rounded up to 5 skeins. Five skeins give 5 × 220 = 1,100 yd — 100 yd of leftover, a comfortable buffer for swatches and a matching hat.

Frequently asked questions

How do I match the yarn weight?

Compare the pattern's gauge and stated weight class to your substitute. Yarn weights run from lace and fingering through sport, DK, worsted and bulky, and each has a rough yards-per-100 g band: lace 600+, fingering ~400, sport ~300, DK ~230, worsted ~200, bulky ~120. Knit a gauge swatch to confirm before committing.

Why round up the number of skeins?

You can only buy whole skeins, and finishing a project even a few yards short usually means buying another skein from a different dye lot that may not match. Rounding up — and often adding one extra skein for large projects — protects against both running out and gauge differences.

Does dye lot really matter?

Yes. Skeins dyed in separate batches can differ subtly in shade, and the seam where two lots meet becomes visible in a finished garment. Buy all your skeins at once with matching dye-lot numbers, and if in doubt buy one spare.

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This calculator is for educational purposes. Double-check important results before acting on them.