When looking up knitting or crochet patterns online, I like to be able to use my stash or another yarn than suggested by the designer. Not everybody can afford the hand dyed yarn used in the original pattern, or one may want to be able to use a commercial yarn because the fiber is different.
What to look for?
In the pattern, sometimes the yarn weight is mentionned. Lace, 4 ply, DK, aran, chunky… are different yarn weights. It means the number of strands plied in the yarn is different. The more strands you have, the thicker the yarn.
Sometimes the designer lets you know how much “ply” (strands) there are in the yarn they used (2 ply, 4 ply, 8 ply…) and you can find a commercial yarn with similar characteristics. Or they use the usual denominations above: lace, 4 ply, DK… Another good indication is the yardage and the gauge given.
Yardage (or meterage)
Usually the pattern mentions how much yarn is needed, as in the number of skeins and also the yardage – the total length of yarn used to make the garment. This is a good indicator to know how much of the yarn you will substitute you need in order to finish the project (and avoid loosing at yarn chicken!!). You will need to compare the yardage of the commercial yarn you choose in respect to the uardage used in the pattern and calculate how much skeins you need:
total yardage in the pattern / total yardage for 1 skein of your substitute yarn = number of substitute skeins needed
For example, if your pattern calls for 3 skeins of 4 ply (sock) yarn amounting to 1500m in total, and you want to substitute with a sock yarn which length is 210m per ball, you wil need just a bit more than 7 balls (divide the total length in the pattern by the meterage of your substitution: 1500/210=7.14), so you will need to get 8 balls to be on the safe side.Just a thought: do not compare yardage (in yards) and meterage (in meters) like I did once…
Next step, you want to knit or crochet a sample to check your gauge in your substitute yarn. It is always a good idea to do so, but if you are substituting yarn, it is essential to make sure your work is true to the pattern and not end up with something way off after hours of hard work. Follow the patterns instructions in order to make your sample. Some pattern ask for blocking, others don’t.
If the sample does not match the pattern’s gauge, adjust your needles or hook size accordingly: if you get more stitches, change to larger needles / hook. If you get less stitches, change to smaller needles / hook.