Double Knitting Calculator — Calculate yarn for reversible double knitting.

Double knitting builds two stitches for every chart cell — a knit on the front in one colour and a purl on the back in the other — so it produces two fabric layers at once. For the same finished width and length, a double-knit fabric uses roughly twice the yarn (and takes roughly twice the time) of a single-layer fabric. Enter your single-layer (flat-equivalent) estimate and the calculator applies the doubling factor (default 2.0) for you.

In reversible two-colour double knitting the two colours are used in approximately equal amounts (about 50/50), no matter what the chart shows. Every front knit stitch in colour A is paired with a back purl in colour B, and the mirror happens on the reverse, so the colours balance out across the whole fabric. Only adjust the split away from 50/50 for designs that are deliberately colour-dominant.

Double knitting has no floats — neither colour is stranded across the back — so there is no float-driven yarn penalty as there is in Fair Isle. The doubled, slightly stiffer fabric tends to knit up looser, so most knitters go DOWN a needle size (often one or two sizes) compared with single-layer knitting to firm up the fabric. Always swatch in double knitting to confirm your gauge before committing.