Yarn Weight Substitution Calculator
Convert a yardage amount from one Craft Yarn Council standard yarn weight to the equivalent yardage of another weight class. Fast, free, and fully client-side.
Calculator Inputs
How the Yarn Weight Substitution Calculator Works
Yarn weight substitution isn't a 1:1 yardage swap — a thinner yarn covers far more distance per gram than a bulkier one, so substituting weight classes at the same yardage produces the wrong amount of finished fabric. This tool converts a source yardage to the equivalent yardage in a target weight class using each Craft Yarn Council (CYC) standard weight category's approximate yards-per-100g. These are representative midpoints for each class, not any specific yarn's label figure — actual yardage varies by fiber content and brand, so treat the result as a shopping estimate, then check the specific yarn's own label.
Formula
Target Yards = Source Yards × (Target Yds/100g ÷ Source Yds/100g)
Approximate yards-per-100g by CYC standard weight class: Lace ≈800, Fingering ≈460, Sport ≈350, DK ≈280, Worsted ≈200, Bulky ≈140, Super Bulky ≈90, Jumbo ≈60.
Calculation Example
Substituting 200 yards of Worsted (≈200 yds/100g) with DK (≈280 yds/100g): 200 × (280 ÷ 200) = 280 yards of DK needed for the same amount of fabric.
Frequently Asked Questions
Why not just buy the same yardage in the new weight?
Yardage alone doesn't tell you how much fabric a yarn produces — a thinner yarn is longer per gram, so the same yardage in a lighter weight covers less area than the pattern needs, and the same yardage in a heavier weight covers more than necessary.
Will substituting yarn weight change the finished size?
Yes, unless you also re-swatch for gauge and adjust the stitch/row counts (see the Knitting Gauge Calculator) — a weight substitution changes the fabric density, so the pattern as originally written will no longer produce the same finished measurements.
Browse more
See all craft tools.