Birt is a lunar impact crater located in the eastern half of the Mare Nubium and west of the Rupes Recta. It was named after British selenographer William R. Birt.
Birt is a bowl-shaped formation with a raised rim, slightly intersected along the southeast edge by the much smaller crater Birt A. To the west of Birt, a rille named Rima Birt runs north-northwest in an arc from Birt F to Birt E.
By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Birt.