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Yarn Held Together Calculator

Pick the yarn weight of each strand you're holding together and we'll tell you the effective weight of the resulting yarn — so you can match it to your pattern.

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Strands held together

Pick the yarn weight for each strand. Add up to 5 strands.

≈ 10 wraps per inch

≈ 10 wraps per inch

How this works

Yarn held together Three yarn strands labelled DK, DK and Lace with their wraps-per-inch flow down and meet at a single point, continuing as one thicker strand whose effective gauge is Aran weight. The strands and the combined strand are one continuous line — never broken. DK 11 WPI DK 11 WPI Lace 18 WPI Effective gauge = Aran 9 WPI Holding yarns together
Three strands (DK + DK + Lace) held together give the effective gauge of a single Aran-weight strand.

Yarn weight categories (lace, fingering, sport, DK, worsted, bulky, super bulky, jumbo) are loosely defined by stitches per inch — but the underlying physical property is yarn diameter, and an easier proxy for diameter is wraps per inch (WPI). The thinner the yarn, the more wraps fit in 1 inch of ruler.

When you hold two or more strands together they bundle into a roughly round cross-section, so the bundle's area is the sum of the strands' areas. Since area grows with the square of the diameter (and diameter ≈ 1/WPI), the combined WPI is the reciprocal of the root-sum-of-squares of the reciprocals: 

combined WPI = 1 / √( (1/WPI₁)² + (1/WPI₂)² + ... + (1/WPI_n)² )

For two equal strands this simplifies to WPI / √2 (about 0.71 × the original). The quick cross-check is grist: yards-per-pound grows with WPI², and holding N strands gives N times the yarn per length, so WPI scales by 1/√N — which is exactly the knitter rule-of-thumb "two strands ≈ one weight category heavier" (two fingering ≈ DK/worsted). The older "add the diameters" shortcut over-thickens by a full category and is wrong.

Why this matters

Patterns specify a yarn weight because it determines the gauge, drape, and fabric feel. If you want to substitute by holding two thinner yarns together — to use stash yarn, to mix colors, or because you can't find the called-for weight — you need to know whether the combination actually matches. This calculator gives you a quick sanity check before you commit to a project.

A note on accuracy

WPI category boundaries are pragmatic, not strict — real yarns span boundaries based on tension, twist, and ply. The calculator gives you the closest category, but treat boundary results as approximate. Always knit or crochet a small swatch before committing to a project. If your combined WPI lands on a boundary, the gauge converter can help you adjust the pattern numbers if your swatch comes out slightly off.

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