Angle of motor rotation and CNC unit relationship

I'm having a problem of find the angle of motor rotation and CNC unit relationship. I mean for 1 inch = 'theta' degrees of rotation in X axis. I tired to measure it but gave no accurate results. Anyone knows to find it mathematically.?
Thank you.

On a normal linear axis (you mentioned X) and assuming a screw for
translating the motor rotary motion to linear motion, this would depend on
the screw pitch. So for example if you had a 5 TPI ballscrew on X,
directly driven by the motor, you would have one motor rotation for 0.200"
of motion or 1800 degrees (5 turns) per inch