If you're talking about the 1st string to the cut in the body, my Tele is only 7.5cm. That has little to do with the distance from the leg, as I often move the guitar left, so that it sits higher and is straighter across my body.
Are you measuring from the center of the leg? Outside of the leg? Inside of the leg?
How much do you weigh? Is one leg fatter than the other? Left leg? Right leg? What in the case of a double amputee?
Are legs spread wide open or closed up tight? Does mental retardation factor into this?
What does any of this matter? Will you send out prizes for winning answers?
I hate to break it to some of you, but the size of a persons leg doesn’t factor into a measurement from leg to first string. Also for OP, if you need to know this measurement you can look up the waist width of most any guitar, as well as width of neck at 12 fret. You can use this specs to determine the measurements you are asking about