How to Substitute Yarn Without Ruining Your Project

The yarn a pattern calls for is discontinued. Or it's $32 a skein and the budget says $12. Or you just found something beautiful in your stash that you want to use instead. Yarn substitution is something every crafter does, and done right, the finished project is just as good as the original.

Done wrong, you end up with a hat that fits no human head.

Here's how to substitute yarn without ruining a project — including how to use the yarn calculator to verify your yardage before you commit.

Step 1: Match the Yarn Weight

This is non-negotiable. If the pattern calls for worsted weight, you must use worsted weight — or match the gauge that worsted achieves (more on that below). Using DK when a pattern calls for worsted makes the fabric smaller and the gauge tighter. Using bulky makes everything bigger and looser.

Check the weight category on the ball band (the symbol with a skein and number 0-7). Match it to the pattern's recommended weight. If the pattern only lists gauge rather than weight, figure out the weight from the gauge — our yarn weight guide includes a gauge-to-weight reference table.

Step 2: Match the Fiber Character

Weight is the hard requirement. Fiber is a softer one — but it matters for how the finished object drapes, stretches, and wears.

Twist: If the original yarn is tightly twisted and structured, a loosely twisted substitute will behave differently. Tightly twisted yarns hold stitch definition for cables and textured patterns. Loosely twisted singles are better for smooth, draping fabric.

Fiber elasticity: Wool stretches and bounces back; cotton and linen don't. If the pattern uses stitch patterns that rely on natural stretch (like ribbing for a fitted cuff), a non-elastic substitute will result in a looser, less structured fabric.

Drape: Silk, bamboo, and Tencel create fluid, drapey fabric. Wool and acrylic create structure. If a pattern is designed as a flowing wrap or shawl, choose a substitute with similar drape characteristics.

You don't need a perfect fiber match — just avoid substitutions where the fiber characters are completely opposite.

Step 3: Match the Gauge — Not Just the Weight

Two worsted weight yarns can have different gauges because of differences in twist, fiber, and manufacturing. The pattern's stated gauge is the target.

Here's the key: your gauge with the substitute yarn must match the pattern gauge, not just the weight category. Knit a gauge swatch with the substitute yarn and the recommended needle or hook size. If you're not matching the gauge:

Too many stitches per inch (tighter) → go up a needle size
Too few stitches per inch (looser) → go down a needle size

Keep adjusting until the gauge matches. The needle size doesn't matter — the gauge does. For a complete walkthrough of measuring and adjusting gauge, read our gauge guide.

Step 4: Calculate the Yardage for the Substitute

This is where crafters most often go wrong. The pattern lists yardage for the original yarn, but the substitute may have a different yardage per skein. If you just buy the same number of skeins, you may not have enough total yards.

Here's the process:

Note the total yards required in the pattern (all sizes, all colors)
Look up the yardage per skein for your substitute yarn
Divide total yards by substitute skein yardage = number of skeins

Example: A sweater pattern calls for 1,200 yards of worsted weight in a yarn that comes in 220-yard skeins. You want to substitute with a yarn that comes in 180-yard skeins.

Skeins needed: 1,200 ÷ 180 = 6.67 → buy 7 skeins

If the pattern doesn't list total yardage (some older patterns don't), you can estimate it with the yarn calculator — enter the project dimensions, yarn weight, and your gauge to get the total yards.

Step 5: Account for Texture Differences

If the original yarn is a smooth single crochet project and you're substituting with a heavily textured boucle, the stitch definition will be lost entirely. If the original is a complex lace pattern and you're switching from a smooth wool to mohair, the lace holes will disappear in the halo.

Substituting within similar texture categories:

Smooth → smooth: Easy, usually works well
Smooth → slightly plied: Fine, minor stitch definition change
Smooth → mohair/fuzzy: Risky — hides pattern details
Smooth → textured/boucle: Major change in appearance

For colorwork patterns specifically, use a smooth yarn so color strands show clearly. Fuzzy or hairy yarns blend the colors together.

When to Substitute Across Weights

Sometimes you want to change yarn weight — knit a lace pattern in fingering instead of the called-for sport, or make a bulky hat in worsted because that's what you have. You can do this, but you must:

Achieve the pattern gauge — adjust needle size until you match
Recalculate yardage — use the yarn yardage estimator with your new dimensions and gauge
Accept that the finished object may look different — finer yarn gives more stitch detail; bulkier yarn gives more texture

Going one weight category up or down is usually manageable. Jumping two or more categories (like fingering to bulky) will result in a completely different-looking object, even if the dimensions match.

Matching Stash Yarn to a Pattern

If you're working from stash rather than buying new, you'll often have yarn without a label. To identify the weight:

Wrap the yarn around a ruler for 1 inch without stretching it (WPI test)
9-12 WPI = worsted, 11-15 = DK, 14-24 = fingering, etc.
Or knit a test swatch and compare your stitch count to standard gauge tables

Once you've identified the weight, use the yarn calculator to estimate how many yards you need and compare to how much you have. This tells you whether your stash yarn is enough before you start.

For more on reading yarn labels to find yardage and weight, see our yarn label guide. For a refresher on the yarn weight categories, see the yarn weight guide.

Substitution Checklist

Before committing to a substitute:

[ ] Weight category matches (or gauge matches)
[ ] Swatch complete — gauge matches pattern
[ ] Total yardage calculated for substitute skein size
[ ] Fiber character is compatible with the pattern's intent
[ ] All skeins purchased from same dye lot
[ ] Pattern has been re-read with substitute in mind (any special yarn requirements?)

A successful substitution comes down to matching gauge, buying enough yardage, and respecting fiber character. Get those three right and the finished object will be indistinguishable from the original.

How to Substitute Yarn Without Ruining Your Project