Practical guide 3 min read
How to substitute yarn in a knitting or crochet pattern
Buy by length, not skeins or grams, check the thickness with yards per 100 g, and hold thinner yarns double, with worked examples.
Substitute by length, not by weight or skeins
A pattern that calls for "6 skeins" means 6 skeins of its yarn. Your yarn's skeins are almost certainly a different length, so the number of skeins won't carry over. Neither will the weight: two yarns can weigh the same and differ a lot in length.
Work out the total length the pattern needs, then divide by the length of one of your skeins. Open the Yarn Substitution Calculator to do both steps and check the thickness at the same time.
A worked example
A sweater pattern calls for 6 skeins of a worsted yarn with 220 yards in each 100 g skein. You want to use a yarn with 200 yards per 100 g skein.
- Length needed: 6 × 220 = 1,320 yards.
- Skeins of your yarn: 1,320 ÷ 200 = 6.6, so 7 skeins, with 80 yards left over.
Had you bought by weight, 6 skeins (600 g) of a yarn with only 185 yards per 100 g would give you 1,110 yards, over 200 yards short.
Check the thickness first
Yarn weight names like DK, worsted and aran each cover a range, and brands use them differently. A better measure is length per weight, sometimes called grist: yards per 100 g, which is printed on every label.
| Difference in yards per 100 g | What it means |
|---|---|
| Under 10% | A close match; swatch to confirm the gauge |
| 10–20% | Similar; you'll probably need a different hook or needle size |
| Over 20% | A different thickness; the fabric and size will change |
In the example, 200 yards per 100 g against the pattern's 220 is 9% less, so it's a close match, and slightly thicker. A yarn with 185 yards per 100 g is 16% thicker: usable, but swatch carefully.
Fibre moves these numbers too. Cotton and linen are heavier than wool, so a cotton yarn shows fewer yards per gram than a wool of the same thickness.
Holding two strands together
Two strands of a thinner yarn held together work up roughly like one thicker yarn: two strands of fingering are close to DK, and two of DK close to aran. You need twice the length.
For the sweater above, a fingering yarn with 420 yards per 100 g held double behaves like a yarn of 210 yards per 100 g, within 5% of the pattern's. You'd need 2 × 1,320 = 2,640 yards: 7 skeins of 420 yards.
Substitute a yarn, step by step
- Under The pattern gives, choose Skeins and enter the skeins, length and weight of one skein from the pattern's materials list. If the pattern gives only a total length, choose A total length.
- Under Your yarn, enter the Length per skein and Weight per skein from your yarn's label.
- Set Strands held together if you'll hold your yarn double.
- Read Skeins to buy and the thickness check under it.
Before you start the real thing
Swatch in the new yarn with the pattern's hook or needles, wash and block the swatch the way you'll treat the finished piece, and measure it. If you have more stitches per inch than the pattern, go up a size; fewer, go down. Matching the gauge is what keeps a sweater the size the pattern says.
Drape matters as well. A plied wool, a chainette and a cotton tape of the same thickness make very different fabrics, so choose a substitute with a similar fibre and construction when the pattern relies on drape or stretch.