Yarn Substitution Calculator

The yarn substitution calculator works out how many skeins of a new yarn you need to replace the yarn in a pattern. Enter the original skein count and yardage plus the new yarn’s yardage, and it matches the total length so you buy the right amount.

How the yarn substitution calculator works

Patterns are really specified in total length, not skeins, so substituting yarn is a length problem. The yarn substitution calculator multiplies the original number of skeins by the original yards per skein to find the total yardage the pattern needs, then divides by the new yarn’s yards per skein and rounds up.

This is why two yarns can call for very different skein counts even for the same project: a 210 yard skein and a 364 yard skein cover the pattern with different numbers of balls. Matching total yardage guarantees you have enough length, though you should still match yarn weight and gauge so the finished size and drape stay true to the pattern.

Worked example

Suppose a pattern lists 8 skeins of a yarn with 210 yards each. Multiplying 8 by 210 gives 1,680 yards, the true amount of yarn the project needs.

You want to substitute a yarn that comes in 364 yard skeins. Dividing 1,680 by 364 gives 4.6, which rounds up to 5 skeins. You would buy 5 skeins of the new yarn, ideally from a single dye lot, to complete the project, with a small amount left over for a matching border or future repairs.

Matching more than yardage in the yarn substitution calculator

Yardage tells you how much to buy, but weight and gauge decide whether the substitute will actually work. Choose a replacement in the same weight category and check that its recommended gauge matches the pattern. The Craft Yarn Council Standard Yarn Weight System makes it easy to compare categories from lace to jumbo.

Fiber content matters too: a drapey bamboo behaves very differently from a springy wool even at the same weight. Always crochet or knit a gauge swatch in the new yarn before committing, and buy one extra skein for safety. For help identifying an unlabeled yarn’s weight, the wraps-per-inch method from the Craft Yarn Council is a reliable check.

Related calculators: All craft calculators · Yarn Yardage Calculator · WPI Yarn Weight Calculator

Frequently asked questions

How do I substitute one yarn for another?

Match the total yardage, not the skein count. Multiply the pattern skeins by its yards per skein, then divide by your new yarn yards per skein and round up. Also match the weight and gauge so the size stays correct.

Why does the skein count change?

Because skeins hold different amounts of yarn. A pattern needing 1,680 yards takes 8 skeins at 210 yards each but only 5 skeins at 364 yards each. The total length is what stays constant.

Do I have to match yarn weight?

For a faithful result, yes. Substituting a different weight changes the gauge, and therefore the finished size and drape. Stay within the same weight category and confirm with a swatch before starting.

Does fiber content matter when substituting?

It does. Cotton, wool, acrylic, and bamboo drape and stretch differently even at the same weight. Swatch the new yarn to check the fabric feels right for the project, especially for garments.

Should I buy an extra skein?

Yes. Rounding up covers the yardage, but one spare skein from the same dye lot protects against gauge differences and mistakes, and keeps the color consistent if you need it for repairs later.