If it is how you measure you request,
For 2 piece I usually follow this:
If you are just starting, it is best to start by measuring with a yard stick to begin with, and once you have done enough, and have a good feel for the stringing process, then, I do this:
Mount racquet on machine:
Measure out: (since most racquets are 27"long)
9 racquet lengths= 20.25' = most mains
8 racquet lenghts=18'= most crosses
You can readjust from there once you know certain racquets, but this give you a good ball park starting point and handles most racquets out there, and if you ever get a little short, a starting clamp comes in handy for extending the length to tension , so you can finish the job. A starting clamp is a cheap enough well worth while tool to have.