How to use it
- Knit a swatch in stockinette stitch, wash and dry it as the finished piece will be, then count the stitches and rows over the measured width and height.
- Type the count in Stitches in the swatch and Rows in the swatch, and the measured width and height in centimetres.
- Type the size you want in Width you want and Length you want, and the number of stitches in one Pattern repeat.
- Read Stitches to cast on and Rows to knit, then check Width those stitches make against the width you want.
How the stitches and rows are worked out
A swatch gives the gauge: the stitches counted across a measured width, and the rows counted over a measured height. Dividing the stitches by the width gives stitches per centimetre, and dividing the rows by the height gives rows per centimetre.
The tool then multiplies the width you want by the stitches per centimetre, and the length you want by the rows per centimetre. Stitches are rounded to whole pattern repeats and rows to whole rows.
stitches to cast on = width × stitches per cm, rounded to a whole repeat; rows = length × rows per cm, rounded to a whole rowYarn weight categories
The Craft Yarn Council's Standard Yarn Weight System gives a stitch range for each category, counted in stockinette stitch over 4 inches (10.16 cm). The tool converts your gauge to stitches in 4 inches, rounded to a whole stitch, and shows the category or categories that hold it.
Two ranges overlap, so 23 and 24 stitches are both fine and light. The council calls its figures guidelines only, so the gauge in your pattern is the one to match.
| Category | Stitches in 4 inches |
|---|---|
| 0 Lace | 33 to 40 |
| 1 Super fine | 27 to 32 |
| 2 Fine | 23 to 26 |
| 3 Light | 21 to 24 |
| 4 Medium | 16 to 20 |
| 5 Bulky | 12 to 15 |
| 6 Super bulky | 7 to 11 |
| 7 Jumbo | 6 and fewer |
What the tool does not cover
- It does not know the stitch pattern. A rib, a cable or a lace pattern has a different stitch count, so measure the swatch in the pattern you will knit.
- It does not work out increases, decreases or shaping. Add those from the pattern once the cast-on is right.
- It does not replace the swatch. Many yarns change size after the first wash, so wash and dry the swatch before you count.
Worked example: 50 × 70 cm at 20 stitches and 28 rows per 10 cm
A swatch of 20 stitches and 28 rows over 10 × 10 cm gives 2 stitches and 2.8 rows per centimetre. For a width of 50 cm, 50 × 2 = 100 stitches. For a length of 70 cm, 70 × 2.8 = 196 rows.
The 100 stitches make 100 ÷ 2 = 50 cm, and the 196 rows make 196 ÷ 2.8 = 70 cm. In 4 inches, 2 stitches per cm give 20.32 stitches, which rounds to 20: the medium category, number 4.
| Item | Result |
|---|---|
| Stitches to cast on | 100 |
| Rows to knit | 196 |
| Yarn weight | Medium (4) |
Frequently asked questions
Why do I need a swatch when the pattern gives a gauge?
A pattern's gauge is the one its designer knitted, with their yarn and their hands. Your own swatch shows how your knitting compares, so the finished piece comes out the size the pattern intends.
Do I count the stitches in stockinette stitch?
Yes. The Craft Yarn Council's ranges are for stockinette stitch, which is knit on the front and purl on the back. A rib, garter or lace pattern counts differently, so measure the swatch in the pattern you will knit.
Why is the cast-on rounded to a pattern repeat?
A pattern such as 2 by 2 rib needs a whole number of repeats across the width. With a repeat of 4, 100 stitches stay 100, but with a repeat of 3 the 100 stitches become 99, which is 33 repeats.
Why does a gauge fall into two yarn weight categories?
The council's stitch ranges overlap: 23 and 24 stitches in 4 inches are both fine and light. The tool lists both, and the yarn label or the pattern settles which one applies.
Why does the tool convert to 4 inches when I measure in centimetres?
The council counts stitches over 4 inches, which is 10.16 cm, because one inch is exactly 2.54 cm. The tool converts your count to stitches per 4 inches, so the category matches the council's table.
Should I wash the swatch before I measure it?
Yes, if the finished piece will be washed. Many fibres change size after the first wash and dry, so measure the swatch in the state the piece will be used in.
Sources
- Craft Yarn Council, Standard Yarn Weight System (knit gauge ranges in stockinette stitch to 4 inches)
- NIST Guide to the SI, Appendix B.8: inch (in) = 2.54 cm exactly (NIST SP 811)
Figures and text last checked on Wednesday, November 11, 2026.