About the Yarn Calculator
This yarn calculator estimates how much yarn a knitting or crochet project needs from a simple measurement: the weight of a swatch made with your yarn, hook or needles and stitch pattern. Enter the swatch size and weight, the yards and grams on the yarn label, and the size of your blanket, scarf, hat or sweater, and it scales the swatch up to the whole project and tells you how many skeins to buy.
Because the estimate comes from your own swatch, it automatically reflects yarn thickness, stitch pattern (cables and bobbles use far more yarn than stockinette), and how tightly you work. That makes it more reliable than generic charts when you substitute yarn or design your own piece.
Use the same length unit (inches or centimetres) for the swatch and the project. Hats are treated as a tube (circumference × height), and sweaters as a body tube plus two tapered sleeves; ribbing, collars and seams are covered by the extra percentage. Buy all skeins from the same dye lot.
With the default inputs, the yarn needed is 3,630 yd. Change any value above to recalculate instantly.
How to use the yarn calculator
- 1Make a swatch at least 4 × 4 in (10 × 10 cm) in your yarn and stitch pattern, then block it.
- 2Measure the swatch and weigh it in grams, trimming off loose tails.
- 3Enter the yards and grams printed on the yarn label.
- 4Choose the project type and enter its finished size in the same unit as the swatch.
- 5Add an extra margin and read the yards and skeins to buy.
Formula and method
A swatch knitted or crocheted in your project’s yarn and stitch uses yarn at the same rate per square inch (or square centimetre) as the finished piece. Weighing it gives grams per unit of area, and the yarn label converts grams to yards. Multiplying by the project area scales that rate up to the whole project.
Blankets and scarves are length × width. Hats and cowls are a tube: circumference × height. A sweater is approximated as a body tube (chest × length) plus two sleeves treated as tapered tubes (length × the average of upper arm and cuff). The extra percentage covers ribbing, edgings, seams, gauge drift and weaving in ends, and skeins are rounded up.
- Swatch area
- Swatch width × height in the same unit as the project
- Project area
- Surface area of the finished piece
- Extra%
- Allowance for edging, seams and safety
Worked examples
Worsted 50 × 60 in throw blanket
The 4 × 4 in swatch weighs 8 g, so the yarn uses 0.5 g per sq in. A 50 × 60 in blanket is 3,000 sq in, or 1,500 g; adding 10% gives 1,650 g. At 220 yd per 100 g that is 3,630 yd — 16.5 skeins, so buy 17.
Beanie in bulky yarn, measured in centimetres
A 50 cm × 22 cm tube is 1,100 sq cm. The 10 × 10 cm swatch weighs 12 g, so 0.12 g per sq cm × 1,100 = 132 g, plus 15% = 151.8 g. At 1.06 yd per gram that is about 161 yd, so two 106 yd skeins.
DK sweater, 40 in chest
The body tube is 40 × 24 = 960 sq in and two sleeves add 2 × 18 × (13 + 8) ÷ 2 = 378 sq in, for 1,338 sq in. The 6 g swatch means 0.375 g per sq in, so 501.75 g, or 577 g with 15% extra for ribbing and seams. At 2.3 yd per gram that is about 1,327 yd — six 230 yd skeins.
Frequently asked questions
How much yarn do I need for a blanket?+
It depends on yarn weight, stitch and size. A worsted-weight 50 × 60 in throw typically needs roughly 2,500–3,600 yd; a swatch-based estimate like this one is the most reliable way to find your number before buying.
How do I estimate yarn from a swatch?+
Weigh a blocked swatch and divide by its area to get grams per square inch. Multiply by the project area for total grams, then convert to yards using the label (yards ÷ grams per skein). Add 10–15% for edges and seams.
How many skeins of yarn do I need for a sweater?+
An adult pullover usually takes about 1,000–1,800 yd of DK or worsted yarn, or 5–9 skeins of 200–220 yd, depending on size, ease, length and stitch pattern. Cables and textured stitches can add 20–30% or more.
Does crochet use more yarn than knitting?+
Usually yes — crochet stitches are taller and thicker, so a crocheted fabric generally consumes noticeably more yarn per square inch than stockinette knitting in the same yarn; dense stitches such as single crochet use the most. Because this calculator is based on your own swatch, it already accounts for the difference.
Why buy yarn from the same dye lot?+
Skeins dyed in different batches can differ slightly in shade, which shows as a stripe in the finished piece. Buying every skein (plus a spare) with the same dye lot number on the label avoids it.