Yarn Requirement Calculator
Knit a 10 cm square and weigh it: that tells you the grams per square centimetre. Multiply by the area of the finished piece and you have the yarn weight. The figure printed on a pattern assumes the pattern gauge, so it drifts as soon as yours differs.
Your numbers
Yarn needed
360g
Spare
54g
Formula
Yarn needed = Finished width × Finished length ÷ Swatch area × Swatch weight
Add about 15% spare. Sleeves, necklines and finishing eat more than the flat area suggests, and once a dye lot sells out the same shade is hard to match.
What to enter
| Input | Default | Accepted range |
|---|---|---|
| Finished width (cm)The width when finished, before any seam or fold allowance. | 50 | 1 and up |
| Finished length (cm)The length when finished. | 60 | 1 and up |
| Swatch area (cm²)Area of the swatch — a 10 cm square is 100 cm². | 100 | 1 and up |
| Swatch weight (g)What that swatch weighs; weigh it knitted, not unravelled. | 12 | 0.1 and up |
Step by step
Quick reference table
Results when only Finished width (cm) changes and everything else stays put.
| Finished width (cm) | Yarn needed (g) | Spare (g) |
|---|---|---|
| 25 | 180 | 27 |
| 37.5 | 270 | 41 |
| 50 | 360 | 54 |
| 75 | 540 | 81 |
| 100 | 720 | 108 |
What each result means
| Result | At default values |
|---|---|
| Yarn needed (g)The yarn weight in grams, not a number of balls. | 360 |
| Spare (g)The margin you keep for finishing and dye-lot mismatch. | 54 |
Common mistakes
Add about 15% spare. Sleeves, necklines and finishing eat more than the flat area suggests, and once a dye lot sells out the same shade is hard to match.
Glossary
- Finished width
- The width when finished, before any seam or fold allowance.
- Finished length
- The length when finished.
- Swatch area
- Area of the swatch — a 10 cm square is 100 cm².
- Swatch weight
- What that swatch weighs; weigh it knitted, not unravelled.
- Yarn needed
- The yarn weight in grams, not a number of balls.
- Spare
- The margin you keep for finishing and dye-lot mismatch.
Frequently asked questions
Q. How is Yarn Requirement Calculator calculated?
Yarn needed = Finished width × Finished length ÷ Swatch area × Swatch weight — Knit a 10 cm square and weigh it: that tells you the grams per square centimetre. Multiply by the area of the finished piece and you have the yarn weight. The figure printed on a pattern assumes the pattern gauge, so it drifts as soon as yours differs.
Q. Can you walk through an example?
With Finished width 50cm, Finished length 60cm, Swatch area 100cm², Swatch weight 12g, the answer is Yarn needed 360g.
Q. What do I need to enter?
Enter Finished width, Finished length, Swatch area, Swatch weight. The result recalculates as you type, and an empty box counts as zero.
Q. How much does the answer move if I change a number?
Changing only Finished width (cm) moves the answer to Finished width (cm) 25 → Yarn needed (g) 180 and Finished width (cm) 100 → Yarn needed (g) 720. The table below lays out five steps.
Q. How are the numbers rounded?
Money is shown to the nearest whole unit, percentages to one decimal place and everything else to two. What you see is rounded; the calculation itself carries the unrounded value forward.
Q. Anything to watch out for?
Add about 15% spare. Sleeves, necklines and finishing eat more than the flat area suggests, and once a dye lot sells out the same shade is hard to match.
Related calculators
Materials differ in density and absorption. If your label states a figure, use it — the defaults here are only common values.