The length of stitches, or conversely the distance between holes, gets measured in various ways. So do the tools used to make and mark stitch holes.
US and British sewing machines, as well as overstitch wheels, pricking irons, and stitching chisels, are often measured in stitches per inch. French pricking irons from makers like Vergez Blanchard are measured in stitches per Paris inch, which is slightly longer than the British and American inches.
Some older Japanese tools are measured in teeth per sun, a traditional Japanese unit.
More recent manufacturers often state sizes as distances between the points of tines or between the leading edge of each tine to the tailing edge of the next.
| Stitches Per Inch | Distance Between Hole Centers | ||
|---|---|---|---|
| Decimal Inch | Fractional Inch | Millimeters | |
| 1 | 0.5 | 1 / 2 | 12.7 |
| 2 | 0.3 | 1 / 3 | 8.46 |
| 3 | 0.25 | 1 / 4 | 6.35 |
| 4 | 0.2 | 1 / 5 | 5.08 |
| 0.196850393700787 | 5 | ||
| 5 | 0.16 | 1 / 6 | 4.23 |
| 0.15748031496063 | 4 | ||
| 3.8 | |||
| 6 | 0.142857142857143 | 1 / 7 | 3.62857142857143 |
| 3.38 | |||
| 7 | 0.125 | 1 / 8 | 3.175 |
| 0.118110236220472 | 3 | ||
| 8 | 0.1 | 1 / 9 | 2.82 |
| 2.7 | |||
| 9 | 0.1 | 1 / 10 | 2.54 |
| 10 | 0.09 | 1 / 11 | 2.309 |
| 11 | 0.083 | 1 / 12 | 2.116 |
| 0.078740157480315 | 2 | ||
| 12 | 0.0769230769230769 | 1 / 13 | 1.95384615384615 |
| 13 | 0.0714285714285714 | 1 / 14 | 1.81428571428571 |
| 14 | 0.06 | 1 / 15 | 1.693 |