 Thebe is irregularly shaped, with the closest ellipsoidal approximation being 116×98×84 km.Its surface area is probably between 31,000 and 59,000 (~45,000) km2.Its bulk density and mass are not known, but assuming that its mean density is like that of Amalthea (around 0.86 g/cm3), its mass can be estimated at roughly 4.3 kg.