Just did some testing. I believe 10 stitches per inch would be the norm, you would have to measure over 1" and count, and the number shown on the machine is the stitch length in millimetres. The default value may be different with brands, but you may be able to reset that if you go into the machines' control panel. I have 2 Brothers and both are set to 2.5, this gives me 11 stitches per inch [spi]. For paper piecing I reduce to 1 or 1.5. Can you buy tape measures with both inches and mm's and test on a firm [starched?] piece of plain coloured homespun, it's really worth the experiment. I can flip from inches to metric easily, as I went through school with inches, and we - Australia - changed to metric when I was 20. Hope this explains all. Enjoy testing.