According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Thrasymedes measures 34.28 kilometers in diameter and its surface has an albedo of 0.066, while he Collaborative Asteroid Lightcurve Link assumes a standard albedo for a carbonaceous asteroid of 0.057 and calculates a diameter of 35.12 kilometers based on an absolute magnitude of 11.0.
