The question comes up every so often at the knitting meet-up and in the Ravelry forums. It takes the form of “Can I use this yarn instead of that yarn?” and any of a number of variations. And the answer is almost always: “It depends.”

Oh, we want this answer to be a simple “Yes”. But it seldom is. Usually the knitter has a valid reason for wanting to use a different yarn than what was used in the printed pattern: Lack of availability, wanting/needing a different colorway, dislike of the particular yarn, etc. If the knitter happens to select a yarn of similar weight and make-up, the substitution will probably go reasonably well – providing, of course, that the knitter can achieve the stated pattern gauge with the chosen yarn. This is the happiest of all occurrences – the yarn you want to use works out well with the pattern and you can just relax and knit happily on your project.

The subject of matching gauge could constitute the contents of an entire article, if not a book. For the sake of brevity, I will simply state that gauge is essential and that any knitter who wishes to produce a well-fitting garment needs to pay attention to gauge – IF she is following a pattern that contains the concept of “fit” as part of the design. (Gauge is less important with scarves & shawls).

Lindy’s Advice #1: When substituting yarns, it is best to select a yarn that is of the same weight and has the same characteristics as the original yarn. But do a gauge swatch to make certain you do not need to make adjustments so that the garment fits correctly.

Perhaps the most frustrating of experiences with yarn substitution is the situation where you have selected a yarn of similar weight and characteristics – but try as you may, you cannot achieve the stated gauge. The advice is usually to go up a needle size or two if your gauge has more stitches and to go down needle sizes if your gauge has fewer stitches. If this works, then wonderful! Proceed with the project. But if, in spite of the change in needle sizes, you still cannot get the stated gauge – well, this can be a significant problem. Being off a half a stitch doesn’t seem like much, but when multiplied over a large number of stitches (say 100 or more), it becomes quite significant and the result is a garment that doesn’t fit properly. You have two options in this situation: 1) try a different yarn (yep, try another one) ; or 2) get out your calculator and start calculating the adjustments needed to ensure a proper fit.

Note: If math makes you anxious and you would never consider recalculating the number of stitches you need to make the garment using your yarn and your gauge – then skip this next part.

Adjusting pattern length may or may not require some math. If the pattern has instructions that use length (inches) rather than rows, it really isn’t necessary to calculate the number of rows required with your gauge, because you can simply knit to the desired number of inches.

However, if the pattern contains instructions such as “knit 40 rows then begin shaping” – you may want to calculate the adjustments needed, as follows:

This can be a daunting bit of calculation – but it will result in a better fitting garment with your desired choice of yarn and is thus, worth the effort.

So far, I have discussed what considerations are needed when substituting a yarn of similar weight and characteristics with another. Now about substituting an entirely different weight of yarn…

I have attempted this several times and have not been happy with the result each time. Hence, Lindy’s Advice #2: No matter how much you love the yarn you want to substitute and the pattern, if the yarn is not the same weight and/or does not have the same characteristics as the yarn used in the pattern – DO NOT use that yarn with that pattern.

I know, I know – you really want to use this yarn, but it’s like trying to fit a square peg in a round hole. I feel your pain, I really do. But don’t do it, you won’t be happy with the result.

I think every knitter has tried using bulky yarn for a worsted weight pattern or visa versa. The results have probably been disappointing and the garment was either too big or too small. It certainly was for me.

I know of many knitters who have attempted to double-strand worsted weight or sport weight yarn to substitute for bulky weight. It can be done with some success, but once again – you have to do a gauge swatch and make the necessary adjustments for differences between your gauge and the pattern gauge. You just can’t get away from the math…

But wait! There is a way to substitute yarn so that it doesn’t drive you crazy: “Free yourself from the pattern”.

Huh? What do I mean by that? Well, as a knitter you will eventually reach a point in your knitting experience when you begin to understand the basics of garment design and construction. Granted there are literally hundreds of thousands of written sweater patterns available. But any sweater has a front, a back, two sleeves and a neck. If you understand how to construct the basic parts and match them to your desired body measurements – you really don’t need a specific written pattern.

Let’s start with that pattern you want to knit with a different weight of yarn. What are the characteristics of the garment? How are the sleeves shaped? How is the front shaped and how is the back shaped? What do you like about this pattern?

Does the pattern use a textured stitch patterning or does it have a particular colorwork patterning? Are there charts for the stitch pattern(s) or the colorwork pattern(s)? You can use these to make your own customized sweater with your chosen yarn.

How? Well, it will require some thinking, some planning, some math (sorry!) and a very good set of body measurements. Armed with the knowledge of sweater design – you can go from carefully following a written pattern to using the pattern as an inspiration for your own custom designed sweater.

I will outline how to do this in my next post. Off to find my sweater design references…