Joystick servo control axis value when idle (unity)


When the joystick servo control is idle (user not moving it) , i don’t believe the axis value will be 0 because there’s a lot of thing that interfere with the value (such as calibration , inaccuracy , physics problem in real life , ect . . ) . Is anybody have tested at which range the joystick servo control axis value is safe to be considered as idle? (both negative and positive) . I’m looking for constants here.

To anyone confused what does i meant with joystick servo control , picture below :
(ps : not my image, i found it on google)

joystick servo control