Multicoloured balls of yarn ranging from dark blue to vibrant pink

How to: Substitute yarn

It can be disheartening when you find a pattern that you love, but is for a yarn that you either can’t wear or can’t afford. But that doesn’t mean you can’t create the pattern of your dreams. This is where yarn substitution comes in.

For some this can seem quite scary as it isn’t an exact science and requires some thought, as well as trial and error, so here are a few pointers to help you feel more confident as you start on your own yarn substitution journey.

Look carefully at the yarn the designer has used

Is it soft or strong? Is the finished fabric firm or does it have drape? If you want your finished item to perform in the same way as the original, it is important that the yarn you choose is capable of creating a similar fabric to that in the pattern. For example a 100% merino yarn will not create socks as hardwearing as a wool/nylon blend and an acrylic yarn may not provide the sheen and drape of yarn containing silk. In an ideal world you want to find a yarn that will give you a finished object as close to the sample shown in the pattern as possible. If that isn’t possible, think about which qualities where you are willing to compromise.

Prepare to experiment

Love them or hate them, to be certain that your chosen yarn will work with the pattern, you will need to knit a swatch. It will save you a lot of time and heartache down the road, especially if it doesn’t turn out as you imagined. If you make it fairly large and include the stitch patterns used in the design, this will give you a good idea of whether your yarn will create the kind of fabric and look you’re after.

Check your gauge

Another thing to use your swatch for is to check that your chosen yarn can achieve the gauge given in the pattern. This is crucial if you want your finished item to be the right size. Adjusting the needle size to get the correct gauge may affect the fabric created, so creating a large swatch to the correct gauge will solve both issues at once.

Working out how much yarn you need

If you are substituting a different brand of yarn, or your yarn is made of different materials to the one given in the pattern, you may end up needing more or less than is stated in the pattern. All good patterns should tell you the measurements and the meterage needed for each size. I’m going to use my Borealis socks as an example.

You will need to have a few figures ready.

Weight of your chosen yarn50g
Ball length in meters210m
Weight of your swatch6g
Size of swatch20 x 20 cm

First work out the number of meters per gram of your new yarn.

210 m / 50 g = 4.2 meters per gram

Then work out how many meters you have used in your swatch.

4.2 m /g x 6 g = 25.2m

Next you need to know the overall area of the item you wish to knit. For things such as socks and hats, multiply the finished circumference by the longest length. For garments you will need to work out the area for the body and the sleeves separately and then add them together.

Sock circumference = 19 cm, foot length = 22 cm, leg length = 23 cm

19 x (22 + 23) = 855 sq cms

Then calculate the size of your swatch.

20 x 20 cm = 200 sq cms

Next you need to work out how many of your swatches it would take to make your chosen size.

855 sq cms / 200 sq cms = 4.275 swatches

To find out the total number of meters needed, multiply the number of swatches by the number of meters per gram of your chosen yarn.

4.275 swatches x 25.2m = 107.73m of yarn

Round up to nearest meter and add a buffer of 15%.

108 +15% = 124.2 m

So for me to knit a pair of socks in my new yarn I would need 250 meters of yarn, rather than the 269 meters stated in the pattern.

Most importantly Have fun! 

Substituting yarn is not an exact science as the possible combination of yarn and pattern are endless but with these simple tips, and a little bit of maths. you can have a lot of fun experimenting and learning about different yarns.

The main thing to remember is that as long as the fabric you create does what you want it to do and looks how you want it to look then your finished item will be even more unique to you.


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