The method
One score, built only from yarn physics.
Every substitute is scored from 0 to 100 using six measurable properties. Price, stock and shop commissions are calculated separately and can never move a score.
The six factors
- Gauge35 %
Stitches per 10 cm on the recommended needle. The closest thing to how a pattern will actually come out.
- Meters per 100 g25 %
Compared on a log scale, so a 10 % gap weighs the same for lace and for chunky yarn.
- Fiber content25 %
Fibers are grouped into families — wool, luxury animal, mohair, silk, plant, cellulosic, synthetic — with partial credit between related ones.
- Needle size8 %
Midpoint of the recommended needle range.
- Construction5 %
Plied, singles, tweed, brushed, blown, chainette, bouclé, chenille or tape.
- Care2 %
Machine-washable for a hand-wash yarn is a mild upgrade; the reverse is a real downgrade.
Hard limits
Some differences can't be averaged away. When one applies, the score is capped no matter how well the rest matches.
Max 50 %
Gauge differs by more than 3 sts / 10 cm
Max 50 %
Recommended needles differ by more than 1.5 mm
Max 55 %
Chenille or tape against a regular yarn
Knitter warnings
Shown next to a substitute as advice. They explain the result but don't change the score.
Felting
A superwash substitute for a pure animal-fibre yarn will not felt.
Socks
A reinforced sock yarn swapped for one without nylon will wear faster on heels and toes.
Drape
More plant or silk fibre means heavier drape and less elastic ribbing; more animal fibre is springier.
Blown yarns
Air-filled yarns feel lighter than spun yarns at the same gauge.
Held-together yarns
Two strands are combined into one virtual yarn — meters per 100 g as 1 / (1/A + 1/B), fibers as a weighted blend, a little extra for a brushed strand — and scored with exactly the same engine.
Current algorithm version: 1.1.0. Always knit a swatch.