How do I estimate colour percentages?

Chart your pattern on graph paper and count the stitches of each colour. Divide each colour's stitch count by the total to get the percentage. For repeating patterns, you only need to count one repeat.

Should I buy extra yarn for colourwork?

Yes. Stranded (Fair Isle) knitting carries floats across the back of every row, so it uses roughly 15-25% more yarn than the equivalent plain stockinette — up to 20-30% where floats are long. This single buffer is the "Extra for Colourwork" % in the calculator; it already covers the floats, so do not add a separate float allowance on top. Intarsia uses extra mainly for the tail ends at each colour change rather than floats.

Does colourwork affect gauge?

Stranded colourwork (Fair Isle) typically produces a slightly tighter gauge than single-colour knitting because of the floats. Many knitters go up a needle size for the colourwork section. Always swatch in the colourwork pattern.

KnitCalcs

Fair Isle Yarn Calculator — Calculate yarn per colour in Fair Isle patterns.

Calculate yarn per colour in Fair Isle patterns.

Total Yarn Needed

Plain-stockinette metres for your size — the float buffer is added below, so do not use a colourwork pattern's pre-padded total

Colour 1 %

Share of stitches in the main colour (chart and count one repeat); main is usually ~60%

Colour 2 %

Share of stitches in the contrast colour; Colour 1 % + Colour 2 % should total 100

Extra for Colourwork

Stranded buffer for floats — 15-20% typical, 20-30% for long floats. This is the only float allowance; it is not stacked.

How We Calculate This

Enter the plain-stockinette yardage for your size (from a same-size single-colour pattern, or worked out from the swatch area) and the share of stitches in each colour. The calculator splits that yardage by colour, then adds one colourwork buffer for the floats and a small tail allowance.

The formula

Colour yarn = Total yarn x Colour percentage / 100

With extra = Colour yarn x (1 + Extra %) + (2 x Tail waste)

Worked example: 1200 m, 60% / 40% split, 15% extra, 15 cm tail. Colour 1 = round(1200 x 60 / 100) = 720 m; with extra = ceil(720 x 1.15 + 0.30) = 829 m. Colour 2 = round(1200 x 40 / 100) = 480 m; with extra = ceil(480 x 1.15 + 0.30) = 553 m.

Frequently Asked Questions

Related Calculators

Stripe Sequence Calculator

Calculate yarn needed per colour for striped patterns with custom sequences.

Intarsia Yarn Calculator

Calculate yarn lengths for each colour block in intarsia colourwork.

Colour Block Calculator

Calculate yarn for large colour block sections in garments.

Gradient Calculator

Calculate yarn quantities for gradient or ombre colour transitions.

Mosaic Knitting Calculator

Calculate yarn for mosaic (slip-stitch) colourwork patterns.

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.