Automatic sensor calibration for milling machines

A milling machine includes a milling rotor, at least one leg, a grade sensor, and a control circuit. The milling rotor is configured to engage a surface beneath the milling machine. The at least one leg is controllable to raise and lower the milling machine. The grade sensor is configured to sense a position indicative of a cut depth of the milling rotor, and the control circuit is configured to receive data from the grade sensor. The control circuit is also configured to: identify a distance from the milling rotor to the surface based on a selected position of the at least one leg; identify a value associated with a detected condition using the grade sensor while the at least one leg is at the selected position; and calibrate the grade sensor by associating the identified distance from the milling rotor to the surface and the identified value.