How to find Joystick Axis?

I'm currently using a USB controller and I'm trying to figure out a way to measure / find the exact axis a Joystick is at.

For example I want to Measure weather the Joystick is more left then right if(Input.GetKey(KeyCode.JoystickButton7)){

// find out weather it's left or right

I know from windows calibration default is set to 127,127 so how can I measure that??? any help greatly appreciated thanks...