Yarn Calculator
Multiply the project's area in square inches by a yards-per-square-inch figure for the yarn weight, adjust for the stitch pattern, and divide by the yards per skein — then round up. This yarn calculator estimates total yardage for any rectangular project, tells you how many skeins to buy, and converts to a substitute yarn's put-up so a sale on a different ball size never strands you mid-blanket.
Blanket width, garment back width…
Blank = the 5 sts/in reference for Worsted / aran (4)
From the ball band
Swapping yarn? How many skeins of the new put-up
Buy
7.09 skeins exactly — always round up. Running out mid-blanket means dye-lot roulette.
▸How this was worked out
area = 40 × 60 = 2,400 in²
yardage = 2,400 in² × 0.65 yd/in² (Worsted / aran (4)) × 1 (stockinette) = 1,560 yd
skeins = 1,560 ÷ 220 yd/skein = 7.09
7.09 skeins → buy 8. The yardage table is an empirical estimate (±15%): cables eat more, lace less — weigh a finished swatch for a precious project.
Shopping list
- Worsted / aran (4) yarn1,560 yd total — buy one dye lot8 × 220 yd
- Substitute yarnmatch gauge, not just yarn weight5 × 328 yd
CraftCalc · Yarn estimate
40″ × 60″ in Worsted / aran (4), stockinette
Buy 8 skeins (1,560 yd / 1,426 m at 220 yd per skein)
craftcalc.io — free maker calculators with the arithmetic shown
How do you estimate yarn yardage from project size?
Yarn consumption scales with fabric area: every square inch of knitted fabric holds a roughly fixed length of yarn for a given yarn weight and stitch. Stockinette at worsted gauge eats about 0.65 yards per square inch; fingering packs more stitches per inch and runs ~0.85; bulky runs ~0.55. So the core estimate is yardage = width × length × yards-per-square-inch, multiplied by a pattern factor — cables consume up to 20% more yarn than stockinette, open lace up to 15% less, garter and seed about 10% more.
Then skeins = total yards ÷ yards per skein, rounded up — always up. 4.2 skeins means buy 5, because dye lots change between production runs and a sixth skein bought three months later may be visibly different in the finished piece. If your gauge differs from the weight’s reference gauge, enter it: knitting tighter packs more yarn into the same area, and the estimate scales with the ratio.
Worked example: a 40 × 60 inch worsted throw
A stockinette throw, 40 × 60 inches in worsted at the 5 sts/in reference gauge, from 220-yard skeins. Area: 2,400 in². Yardage: 2,400 × 0.65 = 1,560 yards. Skeins: 1,560 ÷ 220 = 7.09 — buy 8 skeins (1,760 yards), and the extra 200 yards is your insurance against a dye-lot gap and a binding row. If the same throw were a cable pattern, the 1.2 factor pushes it to 1,872 yards — 9 skeins. Cables are hungry.
Substitution: the pattern’s yarn comes in 220-yard balls but the shop has a comparable worsted in 328-yard (300 m) skeins. Same 1,560 yards ÷ 328 = 4.76 — 5 skeins of the substitute. Match gauge, not just the weight label: “worsted” covers anything from 16 to 20 sts over 4 inches, and the substitute must swatch to the same number or the yardage and the dimensions both drift.
Frequently asked questions
How accurate is an area-based yardage estimate?
To roughly ±15% for stockinette-based fabrics — good enough to budget skeins, not to guarantee them. The error sources are gauge (which you can enter), stitch pattern (the factor covers the main ones), and personal tension. For an heirloom piece in one dye lot, knit a 6-inch square, rip it, and measure the yarn used: that scales exactly.
Why round up instead of to the nearest skein?
Dye lots. Yarn is dyed in batches and the same color number varies slightly between them; stores shelve different lots side by side. Running out means hunting a matching lot or living with a visible band. One extra skein is cheap insurance — and most shops let you return unworked skeins.
Do cables really use that much more yarn?
Yes — a cable crosses stitches over each other, which pulls the fabric in and packs more stitches (and yarn) into the same width. Budget 15–25% more than stockinette for heavily cabled fabric; 10% for occasional cables. Lace goes the other way: yarnovers add width without adding yarn.
How do I substitute a different yarn?
Match the gauge, then the yardage: swatch the substitute at the pattern's stitch gauge, compute total yards with this calculator, and divide by the substitute's yards-per-skein. Fibre matters too — cotton is heavier and drapes more than wool at the same gauge, so a cotton substitute changes the fabric's hand even when the math works.
Does this work for garments, not just blankets?
Approximately — enter the garment's total fabric area (back width × length, plus two fronts, plus sleeves) rather than one rectangle. A faster check for garments: most patterns state yardage by size; use that when available, and this calculator when you are designing your own.
Formulas and standard tables are sourced in the methodology. Results are estimates — measure twice, cut once.