How to substitute knitting yarns

Want to use a DK yarn in a pattern that calls for 4ply? Belinda Boaden explains how in her step-by-step guide.

Grey knitted swatch

Every knitter knows this feeling. You see a pattern you know you have to cast on immediately, but a trip to your local yarn shop is out of the question, and you think, ‘I must have something I can use’. A quick flick through the stash yields incompatible yarn, however. Or does it? Can you really knit a design written up for aran-weight yarn in DK or 4ply?


As ever, the answer is ‘yes, depending’. With a willingness to swatch and do a few calculations this may seem daunting, but it doesn’t have to be traumatic!

In the first post in this knitting masterclass we take you through the initial steps of yarn substitution.

First steps in yarn substitution

First of all, consider the yarn the pattern is written for and the yarn you wish to knit it up in. Certainly if it’s your first venture off-piste, then aim to keep within the same fibre family, as that will help to give you a garment that looks and behaves the same way as the sample – a wool-based yarn for another wool-based yarn, for example (as opposed to a cotton or viscose).

Also don’t try to work with a substitute yarn that is hugely different in weight-aran to DK is not too much of a leap, but aran to 4ply might be a step too far for a first attempt at yarn substitution.

Second, consider exactly what you need to do. If it seems just too onerous a task, then go and buy new yarn. Subbing will take effort if you want to be sure of a decent garment, and it’s not wrong or bad to decide that you don’t want to bother.


What is soul-destroying is to start, then get discouraged, not finish it or (even worse) hate what you end up with.

About our expert

Belinda Boaden is a designer and technical expert who works with designers to turn their ideas into written patterns.

Belinda Boaden