To estimate yarn, measure how much your swatch used, then scale that amount by the size of the finished piece. Enter the swatch size and the yarn it used, or weigh it, then enter the finished size and the length in one skein. The calculator returns the yarn needed in yards and metres, and the number of skeins.
How do you use the yarn calculator?
Start with a swatch in the stitch and yarn your project will use, so the swatch behaves like the real thing. Work it, measure it, and note how much yarn it took.
- Choose inches or centimetres, and yards or metres.
- Enter the swatch width and height, measured flat and unstretched.
- Enter the yarn the swatch used. If you cannot measure the length, choose “I weighed it” and enter the grams used and the grams per skein.
- Enter the length per skein from the yarn label.
- Set your margin, which starts at 10 percent and which you can change.
- Enter the finished width and height.
The answer updates as you type, so you can try a different finished size and watch the skeins change.
How does the swatch method work?
The method assumes a piece uses yarn in proportion to its area. A finished piece with 125 times the area of the swatch uses about 125 times the yarn, because the same stitch fills the same space from the first row to the last, and that is why the swatch must use the same stitch, yarn and hook as the project.
The formula is yarn needed = yarn used by the swatch x (finished width x finished height) / (swatch width x swatch height) x (1 + margin / 100). When you weigh the swatch, yarn used = grams used / grams per skein x length per skein. Skeins = yarn needed / length per skein, rounded up. The calculator converts at 1 yard to 0.9144 m.
What does a worked example look like?
Take a swatch of 4 by 4 inches that used 8 yards, a finished piece of 40 by 50 inches and a 10 percent margin. The finished area is 2,000 square inches and the swatch area is 16, so the ratio is 125. Then 8 yards x 125 = 1,000 yards, and with the margin the total is 1,100 yards (about 1,006 m). If one skein holds 200 yards, that is 5.5 skeins, which rounds up to 6.
Those numbers are only an illustration. Your own swatch, size and skein length decide the result.
How much yarn does a blanket, scarf or hat need?
The same steps answer all three questions. For a blanket, the finished width and height are the size you choose or the size your pattern gives. A scarf is a long thin rectangle, so enter its width and height, the height being its length. A hat is not a rectangle, so enter the width and height of the shape as best you can, treat the answer as a rough guide, and raise your margin if you want extra.
This page gives no standard yarn amount for any item. The amount depends on the stitch, the yarn and the size, so only your own swatch can answer it.
What yarn estimate mistakes should you avoid?
- A swatch that is too small. The edges of a swatch can affect the reading, so make it at least 4 inches square. Bigger is better, and 6 to 8 inches square is best.
- A different stitch in the swatch. A swatch in single crochet will not predict a project in a lacy stitch.
- Setting the margin to 0. The margin starts at 10, and the tool uses whatever you enter, so 0 or a cleared box leaves no spare yarn at all.
- Mixing units. Pick one length unit for every size you enter, and let the calculator convert the answer.
Check the weight of the yarn on the yarn weight chart and the hook on the hook size chart. To keep your place while you make the swatch, use the row counter.
Questions makers ask
What if my swatch is not 4 by 4 inches?
Any swatch size works if you enter its real width and height. The tool divides the finished area by the swatch area, so a larger swatch gives a steadier reading. A swatch should be at least 4 in. square, and 6 to 8 in. is better because edges can affect the reading.
What should I do with the result?
Treat it as an estimate. Compare it with any yarn amount your pattern gives, and buy up to the next whole skein. The estimate is only as good as a swatch worked in the same stitch, yarn and hook. This page states no standard amount for any item.
Why does the skein count round up?
The calculator divides the yarn needed by the length per skein and rounds up to a whole skein, so 5.5 skeins shows as 6. In "I know the length" mode the skein length only sets the count, but in "I weighed it" mode it is also needed to find the yarn used.
Does the margin change the skein count?
Yes. The margin adds a percent on top of the yarn needed before skeins are counted, so a larger margin can move the count up a whole skein. In the worked example, 1,000 yards becomes 1,100 yards with 10 percent, which is 5.5 skeins, rounded to 6.
