How to Substitute Yarn When the Called-For One Is Discontinued
When a yarn is discontinued, find a replacement by matching three things in order: fiber content, weight (yards per 100g is more reliable than the label weight), and ply structure. Swatch before you commit to yardage. Most substitutions that fail do so because the knitter matched weight category but ignored fiber behavior or twist.
Why does fiber content matter more than the label says?
Fiber content drives how a yarn behaves on the needle, how it blocks, and how it wears. A 100% merino and a 100% cotton labeled the same weight will knit up differently, block differently, and feel completely different against skin. Matching "worsted" to "worsted" without checking fiber is the fastest route to a sweater that fits on the needles and disappoints off them.
Wool has memory and bounce. Cotton has drape and weight. Acrylic has neither the drape of cotton nor the elasticity of wool. When you're substituting, ask yourself what the original yarn was doing in the pattern. A lace shawl in a silk-merino blend gets its drape from the silk. Swap that for a superwash wool and the shawl will block out but spring back. Not wrong, just different. If the pattern calls for a plant fiber, stay in plant fibers. If it calls for a wool-silk blend, a wool-silk or wool-linen blend will behave closer to the original than a 100% wool.
A useful reference: Ravelry's yarn search lets you filter by fiber content, weight, and yards per 100g. It's the fastest way to find candidates that are actually comparable.
How do I actually compare yarn weights?
Skip the weight category name and look at yards per 100g. Weight category names ("DK," "worsted") are not standardized across manufacturers and mean almost nothing on their own. Yards per 100g is a real number you can compare.
The Craft Yarn Council's standard yarn weight system gives ranges: a DK weight runs roughly 200-250 yards per 100g, a worsted runs roughly 190-240. Those ranges overlap, which is exactly why you can't rely on the label alone. If the called-for yarn ran 220 yards per 100g and you're eyeing a substitute at 190 yards per 100g, that's a meaningful difference in thickness and you'll need to swatch and possibly adjust needle size.
Here's what I actually do: I write down the called-for yarn's yardage per 100g, then search for substitutes within 10-15 yards of that number. If I'm outside that range I'm already fighting the pattern.
What is ply structure and do I really need to care about it?
Ply structure affects stitch definition and how the yarn behaves under tension. Yes, it matters, especially for cables and colorwork. A single-ply yarn and a 4-ply yarn at the same weight will look different in a cable pattern even if you nail the gauge.
Single-ply yarns (like many handspun-style yarns) are soft and halo beautifully but they split on the needle and blur stitch definition. A tightly plied 4-ply or 5-ply yarn will show cables sharply and hold up to frogging without falling apart. If the original yarn was a plied wool and you're substituting a single, expect the texture of the finished fabric to read differently. That's not always bad. A single-ply substitute in a stockinette sweater is usually fine. In a heavily cabled Aran, you'll notice the difference.
How much yardage should I buy?
Buy at least as many yards as the pattern calls for, then add 10%. Substituting yarn almost always means your gauge swatch is close but not identical, and a looser gauge eats more yarn. Running out mid-project is worse than having a leftover skein.
To calculate: take the total yards called for in the pattern, multiply by 1.1, then divide by the yards per skein of your substitute. Round up to the next whole skein. If a pattern calls for 1,200 yards and your substitute comes in 200-yard skeins, you need at least 1,320 yards, which is 6.6 skeins. Buy 7.
If you're buying online and can't return, check whether the retailer sells partial skeins or whether the yarn is widely available so you can reorder. Dye lots matter. Buy from the same dye lot when you can.
Where do I actually find good substitutes?
Ravelry is the most practical tool for this. Search the discontinued yarn, go to its page, and look for the "similar yarns" section or browse the "used in projects" tab to see what other knitters have already swapped in. Someone has probably already done this substitution and noted whether it worked.
Yarnsub.com is a dedicated substitution tool that compares fiber, weight, and yardage and gives you a match score. It's not perfect but it's a fast first pass.
Your local yarn shop is underrated here. If you can bring the pattern or a sample of the original yarn, a good shop employee can feel the yarn and give you a real opinion. That tactile check is something no algorithm does.
What if I can't find a close match?
Swatch aggressively and measure as you go. If you're 10% off on yardage per 100g, try going down a needle size. If the fiber is different, block your swatch the way you'll block the finished piece and see how it behaves. A swatch that's blocked and lived with for a day tells you more than a fresh-off-the-needle swatch.
The honest answer is that some substitutions are compromises. You might get a fabric that's close but not identical. That's fine. Patterns are instructions, not contracts. The goal is a finished object you're happy wearing, not a perfect reproduction of something you couldn't get your hands on anyway.
Frequently asked questions
How do I find a substitute for a discontinued yarn?
Start by identifying your original yarn's key specs: weight category, fiber content, gauge, and yardage per skein. Compare these against candidate yarns rather than relying on brand recommendations alone. Tools like the yarn substitution feature on FiberTools.app let you filter by these attributes simultaneously. Always swatch with the substitute before committing, since even yarns with identical specs can behave differently due to twist, ply structure, and fiber blend.
Does fiber content matter when substituting yarn?
Yes, fiber content significantly affects drape, elasticity, stitch definition, and care requirements. Swapping a wool yarn for cotton, for example, can dramatically change how a finished garment fits and behaves, since cotton has no memory and is much heavier. Try to match fiber families when possible—wool for wool, plant fiber for plant fiber—unless you intentionally want to change the fabric's character. Always check care instructions so your finished project can be washed the same way.
What does it mean to match gauge when substituting yarn?
Matching gauge means your substitute yarn produces the same number of stitches and rows per inch as the original, ensuring your finished piece comes out the correct size. Gauge depends on yarn weight, fiber, twist, and your personal tension. Even if a yarn is labeled the same weight category as the original, always knit or crochet a swatch and measure it before starting your project. Adjust needle or hook size as needed to hit the target numbers.
How do I calculate yardage when substituting a different skein size?
Divide the total yardage required by the project by the yardage in your substitute skein to find how many skeins to buy. For example, if a pattern calls for 1,000 yards and your new yarn comes in 200-yard skeins, you need at least 5 skeins. Always round up by one extra skein to account for swatching and slight variations in your tension. FiberTools.app can calculate this automatically when you enter both yarns.
Can I substitute a different yarn weight if I adjust my needle size?
It is generally not recommended, because changing yarn weight alters more than just gauge—it changes drape, fabric density, stitch definition, and how much yarn you need. Going up or down a full weight category usually requires recalculating the entire pattern. Minor adjustments within the same weight class, such as a light DK versus a heavy sport, can sometimes work with needle size changes and careful swatching, but always verify your row and stitch gauge matches the pattern before proceeding.