675 Ludmilla is a stony (S-type) minor planet orbiting the Sun.

675 Ludmilla is spinning with a period of 7.717 h.[1] In 2012, a study by Benoît Carry gave a meta-estimate of a mass of (1.20±0.24)×1019 kg for Ludmilla, based on a single study of its gravitational influence on other Solar System bodies.

[2] However, given Ludmilla's diameter of 67.7 km (42.1 mi), this mass implies an extremely high density 73.99±15.05 g/cm3.

[2] Because of Ludmilla's small size, its gravitational influence on other bodies is extremely difficult to detect and may lead to highly inaccurate mass and density estimates.

[2] A more recent study in 2019 determined a mass of (6.47±3.14)×1017 kg for Ludmilla, which corresponds to a density of 3.99±1.94 g/cm3 for a diameter of 67.7 km (42.1 mi).