Guides · knitting math, shown in full

How much yarn do you need for a sweater?

Yardage estimates on ball bands and size charts are guesses about an average sweater. Yours is not average — but it is countable. A stockinette stitch consumes a predictable length of yarn, and you know exactly how many stitches your sweater has.

The per-stitch model

yarn per stitch ≈ 3 × stitch width + 2 × stitch height

A stitch is 1/spi wide and 1/rpi tall, so at this example’s gauge (18 sts, 24 rows per 4 in) each stitch uses about 3/4.5 + 2/6 = 1 in of yarn — conveniently, almost exactly one inch at classic worsted gauge.

Count the stitches, then multiply

Back and front: 128 sts × 168 rows, twice.
Sleeves: taper from 44 to 100 sts, so use the average width × 114 rows, twice.
Neckband: 92 sts × 6 rounds.

Multiply the stitch total by 1 in, divide by 36 for yards, and add a 12% safety margin — swatches, seams and woven-in ends are real yarn too. For this oversized pullover the engine’s estimate lands at about 1,867 yd all in: 1863 yd of Denim (9 skeins at 220 yd) — 10 skeins total.

Colourwork changes the split, not just the total

Each charted stitch swaps main colour for contrast one-for-one, and intarsia adds roughly 40% on the contrast side for colour joins and woven-in ends. The arrow motif here needs only 4 yd of contrast — but you still buy a whole skein, so the estimate that actually matters is skeins per colour, in one dye lot each.

The example’s arrow motif — 17 sts × 15 rows on an oversized front.

Get a per-colour estimate for your sweater →It opens live and editable — change any number and the whole pattern re-derives.