Mach is a large lunar impact crater of the class known as a walled plain.

Nearby craters of note include Joule to the northeast, Mitra attached to the western outer rim, and Henyey to the southwest.

The crater Harvey breaks across the eastern rim, and its outer rampart spills across the interior floor of Mach.

The overall shape of Mach resembles a pear, with a prominent outward bulge to the northeast.

By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Mach.