Stitch Density (SPI to SPC)
Translate gauge specs between imperial Stitches Per Inch (SPI) and metric Stitches Per Centimeter (SPC).
Stitch Density Formulas & Rules
How do you convert stitches per inch to stitches per cm? Since one inch equals exactly 2.54 centimeters, the formula is:SPC = SPI ÷ 2.54. For example, a standard sock gauge of 8 stitches per inch translates to approximately 3.15 stitches per centimeter. Conversely, to find Stitches Per Inch from Centimeters, multiply:SPI = SPC × 2.54.
Gauge Calculator
Yarn Weight & Gauge Standards
| Yarn Weight Class | Typical SPI | Typical SPC | Recommended Needle |
|---|---|---|---|
0 - Lace (Fingering) Shawls, fine lace webs, delicate table runners | 8 - 10+ | 3.1 - 4+ | 1.5 - 2.25 mm US 000 - 1 |
1 - Super Fine (Sock) Socks, baby garments, gloves | 7 - 8 | 2.8 - 3.1 | 2.25 - 3.25 mm US 1 - 3 |
2 - Fine (Sport) Lightweight sweaters, thick socks, accessories | 6 - 6.5 | 2.4 - 2.6 | 3.25 - 3.75 mm US 3 - 5 |
3 - Light (DK) Sweaters, light throws, winter accessories | 5.5 | 2.2 | 3.75 - 4.5 mm US 5 - 7 |
4 - Medium (Worsted) Afghans, warm blankets, everyday outerwear | 4 - 5 | 1.6 - 2.0 | 4.5 - 5.5 mm US 7 - 9 |
5 - Bulky Chunky scarves, heavy sweaters, blankets | 3 - 3.5 | 1.2 - 1.4 | 5.5 - 8.0 mm US 9 - 11 |
6 - Super Bulky Rugs, thick cowls, fast-knit throws | 1.5 - 2.5 | 0.6 - 1.0 | 8.0 - 12.75 mm US 11 - 17 |
Why does gauge accuracy matter in knitting?
Knitting gauge or stitch density measures how tightly or loosely yarn is worked. If a design pattern calls for an SPI of 6, but your knitting results in an SPI of 5.5 (slightly larger stitches), your finished sweater could end up multiple sizes too large. When buying yarn from Europe or Japan, their gauges are defined in Stitches Per Centimeter or Stitches Per 10cm. Use our converter above to map their metric standards back to US inches instantly.