A pattern names a yarn because the designer used it. It may be discontinued, too costly, or simply not in the shops where you live. Replacing it is ordinary practice, and it works well when you match the properties that decide how the fabric behaves, rather than the brand.
Start with the weight
Yarn weight is a number from 0 (lace) to 7 (jumbo), shown on the label as a small skein symbol. A pattern that uses a 4 Medium worsted is written for yarn that gives about 16 to 20 single crochet stitches over 10 cm on a hook around 5.5 to 6.5 mm. Replacing it with a 3 Light or a 5 Bulky changes the size of every stitch, and so the size of the whole piece. The yarn-weights database lists each category with its typical hook range and gauge.
If a pattern does not state a weight, find the gauge. The number of stitches over 10 cm in the pattern tells you which weight fits, and you can work up a swatch in a candidate yarn to confirm.
Then match the fibre
Fibre changes how the fabric hangs and behaves more than anything except weight.
| Fibre | Character |
|---|---|
| Cotton | Firm, no stretch, shows stitch definition, heavy when large |
| Acrylic | Soft or crisp depending on the blend, light, holds colour |
| Wool | Springy, warm, fuzzes with handling, blocks well |
| Wool blends | Wool character with less fuzz and easier care |
| Bamboo and rayon | Drapey, slippery, shiny, stretches with weight |
| Linen | Crisp and dry, softens with washing |
A pattern for a stiff basket written in cotton will slump in wool. A shawl written in a drapey rayon will be stiff in cotton. For amigurumi, cotton or a tight acrylic is best since it holds the shape and keeps the stuffing inside; the database of yarn brands lists fibre and weight side by side so you can compare candidates.
Compare yardage, not ball weight
Two skeins of the same weight can carry very different lengths. A 100 g skein of acrylic may contain 170 metres while a 100 g skein of wool holds about 200 and cotton about 180. The pattern may say it needs 450 metres; count the metres, not the number of skeins. To work out how many skeins a substitute requires:
- Take the total yardage from the pattern.
- Divide by the length per skein of the new yarn.
- Round up, and add one more skein if the project uses a large amount, since dye lots vary.
The yarn estimator in the tools section gives the metres a stitch count will need for a stitch type and weight, and the yarn substitute tool takes the yarn a pattern names and the amount required, and lists substitutes from the database with skein counts.
Check drape and stitch definition
Put a skein and a swatch side by side. Look at three things:
- Twist. Tightly plied yarn shows each stitch clearly; loosely plied or single-ply yarn blurs textured stitches.
- Fuzz. A halo makes cables, posts and bobbles hard to read. For patterned stitches choose a smooth yarn.
- Colour. Variegated yarn hides stitch patterns and can pool into stripes. It suits plain stitches.
Make a swatch
Swatching is the step that most people skip and then regret. Work a square about 15 cm across in the stitch the pattern uses, with the hook the yarn suggests, then measure stitches over 10 cm. Compare the result with the pattern's gauge. If you have too many stitches, your fabric is tight; go up a hook size. If you have too few, go down. Hook sizes in the database are listed in metric, US and UK so you can step one size at a time.
For amigurumi, which uses a tighter gauge than garments, choose a hook one or two sizes below the yarn label's suggestion.
Colours and dye lots
When a pattern uses several colours, buy all of one colour at once. Skeins from different dye lots are usually a little different in shade, and the difference shows as a band where the lots meet. If you must join a new lot mid-project, alternate rows of the old and new for a few rounds so the shift is gradual.
A short checklist
- Same weight number, or the same gauge.
- Similar fibre, or a fibre with the same drape.
- Enough metres for the whole piece, plus a spare skein.
- A swatch that matches the pattern's gauge.
- All skeins from the same dye lot.
If those five agree, a yarn from a different maker will work the same as the original.