 40 Leonis is radiating around 4.4 times the Sun's luminosity from its photosphere at an effective temperature of roughly 6,450 K.

An X-ray emission with a luminosity of has been detected from this position, which may be coming from an undetected short-period, low mass companion.40 Leonis has a common proper motion companion, NLTT 23781, with a wide angular separation of 5,230″ (1.453°), corresponding to a physical separation of at least .This magnitude 16.48 star has a class of M5 and is overluminous for its type, which may mean it is a binary system.