Some of us have specific preferences for certain yarn weights. When we see a pattern written for bulky yarn, for example, we wonder if we could adapt it for worsted or DK weight that works better with our body types or our climate. This kind of manipulation actually isn’t that difficult to do, but it does involve some simple mathematics. If you’re willing to grab a calculator and a piece of paper, here is an easy way to substitute a different weight of yarn.

First of all, and of course – be sure to swatch the new yarn to see if the resultant fabric will match the look of the original. If you like the way the swatch looks and think it will substitute well, then you will need to check the gauge that you are getting and then compare it to the gauge given in the pattern. The next step is to determine if there is a size given in the pattern that will give you the desired size.

Most patterns offer a schematic that shows key measurements. Using the bust line measurement is a good starting point for the adjustment. Look at the number of stitches here for the different “sizes.” Let’s say the pattern is written for a gauge of 3.5 inches for bulky yarn, with instructions for finished dimensions of 33-1/4, 36-1/2, 40, 43-1/2, 47, 50-1/4, and 53-3/4 inches, including a 1-3/4 inch button band. You would like to use this pattern with a worsted-weight yarn that knits to 4 stitches to the inch and desire a finished bust measurement of 42 inches. Start by multiplying 42 (the measurement desired) by 4 (the number of stitches you need for each inch of knitting). Your sweater will need one hundred and sixty-eight stitches at the bust area, or 84 stitches for the back. Read over the pattern carefully. You are looking for the number of stitches the pattern uses at the bust area. For this example, a size “50-1/4” uses 170 stitches in the original gauge. Divide 170 by 4 (the new gauge), and you’ll discover that the same instructions, will result in a sweater measure 42.5 inches. Will that half inch matter? If so, can you decrease parts of the finishing? For this example, one could simply make the button band smaller. From here, use the pattern information for the 50-1/4 size to determine how many yards of yarn to buy, and use the pattern as written from here on out.

If the math becomes overwhelming, take the pattern to a local yarn shop and ask for assistance. Because no one shop can stock every single brand of yarn called for in knitting magazines and books, the shopkeepers will be used to making changes like this in order to substitute the yarn in stock instead of what’s called for in the pattern. This is also a great place to ask questions about how the substitution will change the look of the sweater, recommendations for needle size and accessories such as buttons, and the like.

It’s important to realize that some patterns probably shouldn’t be altered in this way. If there’s a great deal of shaping involved, or if the pattern uses techniques such as entrelac that make it difficult to substitute gauge, it’s probably a better idea to use the yarn weight required or choose a different pattern. However, if you take the time to look over the instructions, do a bit of math, and think things through, you will discover that many patterns are not difficult to alter. Knitting takes time and effort – why not give it that extra energy to ensure that your creation is as close to perfect as it can be?