Crochet yarn calculator

Every source we found agrees that your own swatch beats any table, because it captures your yarn, your hook and your tension at once. The method is simple^[5]:

1. Crochet a swatch at least 4 × 4 in (10 × 10 cm) in the pattern's stitch. Bigger is more accurate.
2. Weigh it on a kitchen scale.
3. Divide its weight by its area to get grams per square inch, then multiply by the area of the finished piece.
4. Turn grams into yards with the label: yards = grams × (skein yards ÷ skein grams).

Worked example^[5]: a 6 × 6 in swatch that weighs 18 g is 0.5 g per square inch. A 48 × 60 in blanket is 2,880 sq in, so it needs about 1,440 g of yarn. Put those numbers in the calculator's Swatch tab with your yarn's label and it gives the yards and skeins.

The same source gives a per-stitch version for pieces that aren't rectangles^[5]: a swatch of 20 stitches × 10 rows (200 stitches) that weighs 10 g is 0.05 g per stitch. An 8 × 60 in scarf at that gauge is 40 × 150 = 6,000 stitches, or 300 g, which is 555 yd of a yarn with 185 yd per 100 g.

Two more ways to measure, if you have no scale or no label:

• Frog and measure. Work at least 10 stitches, count them, pull them out and measure the yarn. Length per stitch × stitches per row × rows gives the total^[8].
• Length from weight. Length per gram is the label length ÷ the label grams: 100 m in 50 g is 2 m per gram, so 472 g is 944 m. With no label, weigh a measured 1 m or 1 yd piece instead^[7].

Weighing also answers "how much did I use?" after the fact: the finished piece's grams ÷ grams per skein gives skeins used. Skeins can be a few grams off their label weight, so treat it as close, not exact^[9].

Only one source we found actually measured how much yarn each basic stitch uses. Cookie Snob Crochet worked three squares of about 4.5 × 4.5 in from the same skein of a worsted yarn (I Love This Yarn) on a 5.0 mm (H) hook, weighed each one ten times, then pulled each out and measured the yarn with the tails taken off^[3]. From those measurements:

The source puts the difference plainly: for the same area, single crochet used about 7.3% more yarn than half double crochet and about 24.5% more than double crochet^[3]. A second test with equal 4 × 4 in worsted swatches on a 5.0 mm hook found the same order, sc, then hdc, then dc, with treble using the least^[4]. Its scale had no decimal places, so it gives no figures.

The calculator's stitch-count method uses these measurements as multiples of the stitch's width: 2.17 in of yarn for an sc that is 0.25 in wide is 8.7 stitch-widths. An hdc takes about 12.8 sc-widths and a dc about 16.4. Scaling by width lets the same numbers work for any yarn weight (see section 4).

Worked example, amigurumi. Shiny Happy World's "Jay the Bird" has 1,656 stitches, and the pattern calls for 85 yd^[6]. The source doesn't confirm the yarn weight; worked tightly in worsted, at 4–5 sc per inch, the calculator estimates 80–100 yd, either side of the pattern's figure. That figure may include the designer's own margin, so it is a check, not a measurement.

A dc uses almost twice the yarn of an sc (4.11 in against 2.17 in), but it is about twice as tall, so fewer of them fill the same area^[3]. Per square inch the taller stitch comes out ahead: 1.12 yd for sc, 1.05 for hdc and 0.90 for dc at the same gauge. That is why the calculator asks for your main stitch.

Rough stitch heights in worsted are about ¼ in for sc, ⅓ in for hdc, ½ in for dc and nearly ¾ in for treble^[10].

Treble is an estimate of an estimate. Nobody we found has measured how much yarn a treble crochet uses; one test only reports that it uses less per area than dc^[4]. The calculator offers treble by extending the measured sc, hdc and dc figures to a taller stitch, and labels the result approximate. Use a swatch for any large treble project.

The Craft Yarn Council's Standard Yarn Weight System groups yarn into eight categories and gives a typical crochet gauge and hook range for each^[1]. When you leave the gauge blank, the calculator uses the middle of the council's single crochet range for your weight.

How the calculator scales. It assumes that thicker yarn on a bigger hook makes the same fabric, only larger. Each stitch then uses yarn in proportion to its width, and the yarn per square inch goes up with the number of stitches per inch. This is our modelling assumption, not a published rule, and it is why your gauge matters more than anything else you enter. A gauge measured in hdc or dc is converted to sc width with Cookie Snob's measured widths (hdc 0.265 in and dc 0.281 in against sc 0.25 in)^[3].

Hook size matters only through gauge. No source gives a rule that turns a hook size into yarn, so a hook on its own does not move the estimate. Measure your gauge instead.

Amigurumi is worked tightly, on a smaller hook than the yarn suggests. Two amigurumi patterns give 8 stitches to 2 in and 16–20 stitches to 4 in, both on a 3.5 mm hook^[11][12], which is 4–5 sc per inch. Ticking "Worked tightly" with worsted uses that band and shows a range. For other weights there is no published tight gauge, so the calculator asks for yours.

The Craft Yarn Council's Warm Up America! brochure gives four blanket sizes^[2]. Here is what the calculator gives for each, in worsted yarn at the council's standard gauge (3.125 sc per inch):

For the baby blanket in single crochet with a 219 yd, 100 g skein, that is 1,220–1,330 yd (1,115–1,215 m), or 7 skeins: 6 to cover the estimate and one spare.

• Amigurumi: Jay the Bird, 1,656 stitches worked tightly in worsted: about 80–100 yd against the pattern's 85 yd^[6].
• Scarf: 8 × 60 in, weighed by the stitch: 300 g, or 555 yd at 185 yd per 100 g^[5].
• Throw: 48 × 60 in, weighed by area: 1,440 g^[5].

Size is often the hardest number to pin down for garments and toys. For those, add up the pattern's stitch counts and use the stitch-count method, or weigh a swatch.

• Buy 10–20% more than the estimate, for borders, seaming and the estimate's own error^[5]. Another designer says 15–20% as a rule, 15–25% extra for colourwork, and 20% on the main colour with 10% on the others^[13]. The calculator shows the 10–20% range.
• Round skeins up. Divide the total yardage by the yards in one skein and round up to a whole skein: 1,000 yd of a 103 yd ball is about 10 balls^[15].
• Buy one dye lot, and a spare. "It's important that you always purchase enough of the same dye lot in order to complete your project." Check that the lot numbers match before you leave the shop, and "if you're not sure you'll have enough, buy one extra"^[14]. The calculator's skein count already includes that spare.
• Keep the receipt. "Many allow returns of unused yarn within a certain time frame"^[14].
• Hand-dyed yarn usually has no dye lot. If you run short, alternate skeins every few rows so the change doesn't show as a stripe^[16].

• 1 yd = 0.9144 m exactly, and 1 oz = 28.349523125 g exactly, by the 1959 international yard and pound agreement^[19]. The calculator always shows yards and metres together.
• Substituting yarn: multiply the pattern's skeins by its yarn's length per skein to get the total, then divide by your yarn's length per skein. Three 500 yd skeins are six 250 yd skeins^[5].
• Grams from yards: grams = yards × skein grams ÷ skein yards. This is how the calculator gives a skein count in grams.

Typical lengths per 100 g vary widely, so the calculator's skein field starts with a typical figure and asks you to use your label:

Published per-stitch figures vary a lot. One blanket guide gives about 12 cm of yarn per sc, 15 cm per hdc and 19 cm per dc at 16 sc to 10 cm in worsted^[13]. That is 4.7, 5.9 and 7.5 in, about 2.2 times the measured figures at almost the same gauge^[3], and the guide does not say how it got them. We use the measured figures and treat the difference as a reason to swatch.

Other limits worth knowing:

• The stitch figures come from one careful test with one yarn and one hook.
• Treble and tight amigurumi stitches have not been measured; the calculator's figures for them are extrapolated.
• Fibre may matter: one source says wool runs 5–10% below cotton and stretchy fibres need about 20% more^[13], but gives no measurements, so the calculator does not adjust for fibre.

Taken together: the estimate is a good starting point, the 10–20% margin covers ordinary variation, and a weighed swatch is the only way to be sure.