Réaumur is the remains of a lunar impact crater located on the southern edge of Sinus Medii.

It lies to the northwest of the large walled plain Hipparchus, and east of Flammarion.

The rim of Réaumur is heavily eroded, and the northern half consists of little more than a series of low ridges in the mare.

To the east of the crater rim is a smaller rille designated Rima Réaumur.

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