Crochet Yarn Calculator

How much yarn do you need? Weigh one swatch, enter your yarn label and the size you want to make, and get the total in yards, meters, grams and skeins.

Size in

Yarn length in

Weight in

1. Your swatch

Width

Height

Weight

2. Your yarn label

Length per skein

Weight per skein

3. Finished project size

Blanket size preset (optional)

Width

Length

Extra yarn (safety margin)

For edges, borders, joining and tension changes. 10% is a common margin.

You need about

3,667 yd

of yarn, incl. 10% extra

1,834 g

by weight

19 skeins

of 200 yd / 100 g

Without the margin: 3,334 yd (16.67 skeins). Your swatch used 40 yd, or 1.111 yd per square inch.

How this is calculated

This uses the swatch weight and area method. Crochet a swatch in your project yarn and stitch, then:

Yarn per gram = length per skein ÷ weight per skein (from the yarn label).
Yarn in the swatch = swatch weight × yarn per gram.
Yarn per square inch (or cm²) = yarn in the swatch ÷ (swatch width × height).
Total yarn = project width × length × yarn per square inch, plus your safety margin.
Skeins to buy = total yarn ÷ length per skein, rounded up.

Worked example (from Dora Does): a 15 × 15 cm swatch weighs 20 g. The yarn has 250 m per 100 g ball, so 2.5 m per gram and 50 m in the swatch. That is 50 ÷ 225 = 0.222 m per cm². A 25 × 150 cm scarf is 3,750 cm², so it needs about 833 m, which is 4 balls.

Keep units consistent: measure the swatch and the project in the same unit, and use the same weight unit as your yarn label. Not sure of your gauge yet? Start with the gauge calculator.

Yarn weights and hook sizes

The Craft Yarn Council’s standard yarn weight system, crochet columns. Gauge is single crochet stitches per 4 in (10 cm). These are guidelines; your label and pattern come first.

Weight	Yarn types	sc per 4 in	Hook (mm)	Hook (US)
0 Lace	Fingering, 10-count crochet thread	32–42 dc*	Steel 1.6–1.4 mm; regular 2.25 mm	Steel 6, 7, 8; regular B-1
1 Super Fine	Sock, Fingering, Baby	21–32	2.25–3.5 mm	B-1 to E-4
2 Fine	Sport, Baby	16–20	3.5–4.5 mm	E-4 to 7
3 Light	DK, Light Worsted	12–17	4.5–5.5 mm	7 to I-9
4 Medium	Worsted, Afghan, Aran	11–14	5.5–6.5 mm	I-9 to K-10½
5 Bulky	Chunky, Craft, Rug	8–11	6.5–9 mm	K-10½ to M-13
6 Super Bulky	Super Bulky, Roving	7–9	9–15 mm	M-13 to Q
7 Jumbo	Jumbo, Roving	6 and fewer	15 mm and larger	Q and larger

* Lace weight is usually worked on larger hooks for an open fabric, so the CYC gives a range in double crochet. Source: Craft Yarn Council’s www.YarnStandards.com.

FAQ

How much yarn do I need for a crochet blanket?

It depends on your yarn, hook and stitch, so the most reliable answer comes from your own swatch. Crochet and weigh a small square in the same yarn and stitch, then enter its size and weight here with your blanket size. Pick a size from the blanket presets to save typing.

Why do I need to weigh my swatch?

Weight is the easiest way to measure how much yarn went into a small piece. Your yarn label tells you how many yards or meters are in each gram, so the swatch weight tells you how much yarn it used. The project needs the same amount per square inch.

What scale should I use?

A kitchen scale that measures in single grams works. Use a bigger swatch (for example 6 × 6 in or 15 × 15 cm) so a 1 g rounding error matters less.

Why add extra yarn?

Edges, borders, joining, a slightly looser tension and dye-lot differences all use yarn the swatch doesn’t show. 10% extra is a common safety margin; it is better to buy one more skein from the same dye lot than to run out.

Does this work for amigurumi or garments?

Yes, as long as you can estimate the total area. For a garment, add up the area of each panel. For shaped pieces the result is a rough guide, so add a bigger margin.

Sources

Formulas and standard sizes on this page come from the sources below. Last checked 2026-10-24. Spot an error? Tell us.