Yarn Substitution Calculator: Skeins, Yardage, WPI and Held Double

Using a different yarn than the pattern calls for is one of the most common questions in knitting and crochet. Enter the pattern yarn and your substitute from their ball bands. The calculator converts by total yardage, checks whether the weights match, and handles holding two strands together.

Pattern yarn and your yarn

The pattern calls for

Skeins

Yd each

Grams each

Pattern yarn weight Lace (0)Super Fine (1)Fine (2)Light (3)Medium (4)Bulky (5)Super Bulky (6)Jumbo (7)

Your yarn

Yd each

Grams each

Strands 12 held

Your yarn weight Lace (0)Super Fine (1)Fine (2)Light (3)Medium (4)Bulky (5)Super Bulky (6)Jumbo (7)

WPI (optional)

Wraps per inch

Your results

Skeins of your yarn

8 skeins

1,320 yards needed (8 skeins with 10 percent extra)

Weight check

Same weight range. Swatch to confirm gauge before you cast on.

Pattern total	1,320 yd
Pattern yd per 100 g	220 (Medium)
Your yarn, as worked	185 yd per 100 g (Medium)
WPI suggests	Light or Medium

How do you calculate yarn substitution?

Yarn substitution comes down to one rule: match yards, not skeins. A pattern that says "6 skeins" is really asking for the length of yarn on those skeins. The calculator works in four steps, shown here for the default.

1. Find the pattern's total yardage. Skeins x yards per skein: 6 x 220 = 1,320 yards.
2. Account for strands. One strand needs 1,320 yards. Holding two strands together doubles it to 2,640.
3. Divide by your skein yardage and round up. 1,320 / 185 = 7.14, so buy 8 skeins. With a 10 percent cushion it is 8.
4. Check the weight. Yards per 100 grams = yards / grams x 100. The pattern yarn is 220 and yours is 185. Both fall in the Medium range on retailer charts, so the weights match.

Now the held double version. Suppose you want to use a fingering yarn with 437 yards per 100 grams, two strands at once. You need 2,640 yards of it: 2,640 / 437 = 6.04, so 7 skeins. Two strands together behave roughly like one strand at half the yardage, 218.5 yards per 100 grams, which is inside the Medium range. That makes it a reasonable, approximate stand in for the worsted, pending a swatch.

What is the yarn weight by wraps per inch?

Wraps per inch (WPI) is the old, reliable way to identify yarn with no label: a mystery skein from a destash, a hand spun yarn, or a ball whose band is long gone. Wrap the yarn around a ruler or a WPI tool with the strands touching but not overlapping or stretched, then count how many wraps fill one inch. The Craft Yarn Council publishes a WPI range for each weight, shown below with the retailer yardage ranges and knit gauge.

The WPI ranges overlap, so one count can point to two or three weights; 11 wraps per inch could be Light or Medium. Use WPI together with yards per 100 grams and a swatch. The yardage figures are retailer chart ranges, not a CYC standard, and they vary with fiber, so they are a cross check rather than a verdict.

Does holding two strands of yarn together make a heavier weight?

Yes, roughly. Because two strands use twice the yardage, their effective yards per 100 grams is half of one strand. The table halves each weight's retailer yardage range and shows which single strand weights that halved range overlaps. It is an approximation: two strands are thicker than one but not twice as thick, and held double yarn has a slightly rounder, bumpier texture.

Two strands of super fine, for example, work out to 190 to 300 yards per 100 grams, overlapping Fine or Light or Medium. Where the halved range straddles two weights, the swatch decides which one you really have. Holding double is also a handy way to use up leftovers or blend two colors into a marled fabric.

What should match besides yardage when you substitute yarn?

• Gauge. This is non negotiable for fitted garments. Knit or crochet a swatch with the substitute, wash it, and compare with the pattern gauge using the knitting gauge calculator.
• Fiber behavior. Wool is springy and blocks well. Cotton and linen are heavier and drape downward. Acrylic is easy care but does not open up lace the way wool does. Superwash wool can grow when wet.
• Construction. A plied yarn gives crisp stitch definition for cables; a single ply or a brushed yarn blurs it. Chainette and tape yarns behave differently again.
• Dye lot. Buy every skein at once, from one dye lot, with 10 to 15 percent extra.

If you do not have the pattern's yardage at all, estimate it by project with the how much yarn do I need calculator, then come back here to convert to your skeins.

Can you substitute a yarn when the pattern yarn is discontinued?

Yes, and it is the most common reason to substitute. Older patterns often call for yarns that are no longer made, and the label details are the only clue left. Look up the original yarn's yardage, weight in grams and fiber from the pattern notes or an online yarn database, then enter them as the pattern yarn above. If the pattern only lists the number of balls, search for the ball size: a vintage pattern calling for 50 gram balls needs twice as many as one using 100 gram skeins of the same yarn.

When you truly cannot find the yardage, work backward from the finished measurements and the gauge. Estimate the project total with a yardage guide, add a generous cushion, and swatch in your substitute before buying the full amount.

How do you wind and prepare substitute yarn?

Substitute yarns often come as hanks rather than pull skeins, especially wool and hand dyed yarns, and they must be wound before use. A swift holds the hank open while a ball winder builds a center pull cake. For sweater quantities, the Stanwood Winder + Amish Swift handles 10 ounce cakes, enough for two strands wound together. If the substitute is a category away and you need to swatch on several sizes, a full set such as the HiyaHiya Sharp Expanded 5" means you are never a needle short.