You have found the perfect pattern, and your fingers are itching to cast on. But the yarn the pattern recommends is either discontinued, too expensive, or impossible to source.
Most knitters end up in that situation sooner or later. Finding the right yarn substitution can be tricky. Choose wrong, and you risk a sweater that turns out too big, too small, scratchy, or completely shapeless after the first wash.
There is, however, a systematic method for substituting yarn. It takes a little more work than just comparing yardage, but it gives you a better basis for choosing a substitute.
The three most important factors when substituting yarn
If you want to be confident that your alternative yarn behaves like the original, you need to match three fundamental parameters.
1. Gauge
This is the single most important parameter. If your substitute yarn has a different gauge than the pattern specifies, the finished measurements will be off entirely. Carol Sulcoski, author of Yarn Substitution Made Easy, works through an example with 100 stitches: the difference between four and five stitches per inch (2.5 cm) shifts the circumference of a hat by nearly 13 cm. On an adult sweater, the margin of error is naturally even larger.
Check the ball band on your new yarn for the recommended gauge in stitches per 10 cm. The ball band’s gauge is a starting point. What matters is whether your swatch matches the pattern’s gauge and gives you the fabric you want. A difference of three stitches means you will effectively be knitting a completely different size. A gauge swatch gives you the best basis for judging whether the yarn suits the pattern. Wash and dry the swatch the way you will treat the finished piece, and measure it again. That matters here in particular, because yarn can bloom or stretch in the wash. Measure rows per 10 cm as well as stitches, and knit the swatch in the stitch pattern and the method the pattern specifies, in the round or flat. Row gauge matters for yokes, shaping and pattern repeats. See the full guide to yarn weights for a complete overview of gauges.
2. Yarn construction
Yarn construction describes how the yarn is put together, for example from twisted plies, as a knitted chainette, or from fibres blown into a tube. A singles yarn behaves entirely differently from a four-ply yarn, even if they have the same weight and fibre content.
- Singles (single ply) has a built-in tendency to bias in stockinette when knitted in the round, because the twist of the spinning is not balanced by opposing plies.
- Two-ply yarn works well for light lace patterns. In cables and texture patterns it often gives a flatter relief than a rounder three- or four-ply yarn.
- Three- and four-ply yarn gives a round strand with clear stitch definition, which suits textured work and hard-wearing garments. Whether a yarn is balanced depends on the relationship between the twist in the singles and the ply twist, not on the number of plies.
- Cable-plied yarn (where multiple plied strands are twisted together again) holds its shape exceptionally well and produces a very smooth, durable surface.
- Brushed yarn (such as silk mohair or brushed alpaca) has an airy fibre halo that fills the space between stitches and significantly changes both the look and the warmth of the fabric.
If a pattern is specifically designed for an airy, brushed yarn, you cannot simply swap it for a smooth, multi-ply wool. The fabric can turn out open and see-through, because the smooth strand does not fill the gaps in the same way.
3. Spinning method: woolen vs worsted
Yarn is broadly spun in two different ways, and this has a significant impact on the finished result. Here we are talking about the manufacturing process, not the yarn weight.
- Woolen-spun yarn is made from unsorted fibres lying in all directions. It traps plenty of air inside the strand. The yarn “blooms” and opens up when washed for the first time. It insulates beautifully and has a soft, rustic surface, but it pills somewhat more easily. Classic Icelandic yarn such as Lopi is a typical woolen-spun yarn.
- Worsted-spun yarn is made from long fibres that are combed in the same direction. The twist can be either loose or tight. This produces a compact, smooth and lustrous strand with high stitch definition. It usually pills less than woolen-spun yarn, but twist, fibre length and how firmly you knit also play a part. Many commercial merino yarns are spun using this method.
If you replace a discontinued woolen-spun yarn with a smooth worsted-spun one, you lose the characteristic airiness and the fabric becomes denser. How elastic it feels also depends on fibre, twist and stitch structure.
Overlooked details in yarn substitution
When substituting yarn, three additional elements are often missed.
Fibre content determines drape
It is a common misconception that wool is just wool. If you replace 100% pure wool with an alpaca-wool blend, for example, you will notice significant changes:
- Weight and drape: Alpaca has less crimp than wool, so the fibres pack more densely and hold less air between them. The fabric gets more drape and can stretch lengthwise during wear, because the fibre also has little recovery.
- Elasticity: Alpaca has less elasticity than wool. In a close-fitting ribbed garment, the ribbing can lose its grip over time.
- Surface: Alpaca develops a soft fibre halo over time, changing the look after a few washes.
Superwash vs untreated wool
Superwash covers several treatments. The most widely used one first alters the scales and then adds a thin polymer layer, so the wool becomes resistant to felting. The ball band tells you which cycle and which drying method the yarn can take. It is practical for everyday care, but it changes the yarn’s natural properties:
- The treatment can change elasticity and shape retention, and some superwash yarns stretch in the wash. How much depends on the treatment and on the specific yarn.
- Superwash yarn absorbs dye differently and often appears more lustrous and saturated in colour than untreated wool.
Colour variation and stitch definition
A yarn with large colour shifts, speckles or a marled texture can completely obscure a beautiful stitch pattern. If the yarn is heavily speckled or multi-coloured, the detail in intricate cables and fine lace can drown. A subtle marl or a tweed is less of a risk. In that case, choose a solid-coloured substitute. Simple stockinette patterns, on the other hand, can be lifted visually by choosing a yarn with colour variation.
What does not need to match perfectly?
You do not need to be rigid about every detail on the ball band:
- The brand is irrelevant as long as the technical specifications match. Large producers often make qualities that can substitute for each other. It is the content of the yarn that matters, not the logo on the label.
- Yardage can have some tolerance, provided the gauge matches. If your substitute yarn has a shorter yardage per 50 grams than the original, you need to adjust your total purchase. Convert the original requirement into metres, and from there into whole skeins of the substitute. The same number of grams or skeins is not enough.
When to give up on substituting
Sometimes you have to accept that a substitution simply will not work, because the pattern’s look is entirely dependent on the original yarn’s specific properties.
- If you substitute wool with pure alpaca in a sweater with heavy cables, the pattern can lose some of its definition under the weight, because alpaca has less elasticity than wool.
- If you replace cool cotton or linen with wool in a summer top, you change both drape and warmth. A light wool can work, but a heavier yarn gives you a different garment.
If the pattern’s success depends entirely on a specific structure or drape that your substitute yarn does not have, you will get the best result by finding a different pattern that suits your chosen yarn.
How to find the data for a discontinued yarn
If the ball band is gone and the yarn is out of production, you can often still find the details. Manufacturers frequently keep an archive of discontinued qualities, the pattern itself states the yardage and gauge of the original yarn, and other knitters’ projects show what they used instead.
How Nysta handles yarn substitution
In Nysta you choose the yarn the pattern is written for and get a list of the yarns that come closest. Each suggestion shows how well the yarns match, with a percentage and a green, yellow or red rating. You can limit the list to yarn from your own stash, from the brands you have marked as favourites, or from Nordic producers.
Tap a suggestion to see the two yarns side by side: gauge, yardage, fibre, construction, spin and treatment. You also see similarities, differences and the warnings that apply to the two yarns, such as when one is superwash-treated and the other is not.
When you check your own yarn against a pattern, we also take the pattern’s technique into account, such as cables and ribbing.
Download Nysta on the App Store and try it free for 7 days.
Frequently asked questions
What is the most important thing when substituting yarn? Gauge. If the substitute yarn has a different gauge than the original, the finished measurements will not match. Always check stitches per 10 cm and knit a gauge swatch.
Can I substitute wool with alpaca? It is possible, but be aware that alpaca has less elasticity than wool. Ribbing and cables can lose their shape faster, and the finished piece can drape heavier and stretch over time.
Can I use a cheaper yarn instead of what the pattern recommends? Yes, as long as gauge, construction and fibre type match. The brand and price are irrelevant. It is the yarn’s technical properties that determine whether the result will be good.
Can Nysta help find substitute yarn? Yes. You choose the pattern’s yarn, and Nysta shows a list of substitutes. Each suggestion shows how well the yarns match, with a percentage and a green, yellow or red rating. Tap a suggestion to see the similarities, differences and warnings for the two yarns.
Add your yarn, and we’ll find substitutions that actually work.
Nysta is available for iPhone and Android. You can try it free for 7 days. After that, you can choose a monthly or yearly subscription, and you can cancel anytime.