Fechner is a lunar impact crater that lies on the far side of the Moon's southern hemisphere, attached to the western rim of the large walled plain Planck.

The eastern rim of Fechner intersects the Vallis Planck, a long, wide cleft in the surface that follows a course to the north-northwest.

This satellite crater is surrounded by a blanket of light-hued ejecta that spills across the southwestern half of Fechner's interior floor.

The crater is named after Gustav Theodor Fechner, a German physicist, psychologist, and philosopher (1801-1887).

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