Why does double knitting use about twice the yarn?

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.

How is the yarn split between the two colours?

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.

Does double knitting affect gauge and needle size?

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.

KnitCalcs

Double Knitting Calculator — Calculate yarn for reversible double knitting.

Calculate yarn for reversible double knitting.

Single-layer yarn estimate

Metres for one flat layer — the calculator doubles this for the two-layer double-knit fabric

Colour 1 %

Share of the yarn in colour 1 (usually ~50% for reversible double knitting)

Colour 2 %

Share of the yarn in colour 2 (usually ~50% for reversible double knitting)

Extra for Colourwork

Safety margin to add per colour (15-20% is typical)

How We Calculate This

Enter your single-layer (flat-equivalent) yarn estimate. Because double knitting produces two fabric layers, the calculator multiplies that estimate by the doubling factor (about 2.0), then splits the total between your two colours and adds a safety margin.

The formula

Total double-knit yarn = Single-layer yarn x Doubling factor (~2.0)

Colour yarn = Total double-knit yarn x Colour percentage / 100

With extra = Colour yarn x (1 + Extra %)

Frequently Asked Questions

Related Calculators

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Colour Block Calculator

Calculate yarn for large colour block sections in garments.

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Calculate yarn quantities for gradient or ombre colour transitions.

Last updated: February 2026

All calculations are estimates based on standard yarn weights and gauge. Results may vary with individual tension, yarn brand, and needle size.