[2][12] Located in the outermost part of the main-belt, Oulu is a member of the Hilda family, a large orbital group of asteroids that are thought to have originated from the Kuiper belt.

[12] Oulu is characterized as a dark and reddish P-type asteroid in the Tholen taxonomy, of which only a few dozen bodies are currently known.

[13] In May 2009, a rotational light curve of Oulu was obtained from photometric observations by Slovak astronomer Adrián Galád at Modra Observatory.

[3][9][14] According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite, and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Oulu measures between 65.00 and 91.05 kilometers in diameter, and its surface has an albedo between 0.031 and 0.06.

[5][6][7][8][10] The Collaborative Asteroid Lightcurve Link agrees with IRAS, that is, an albedo of 0.0366 and a diameter of 82.72 kilometers using an absolute magnitude of 9.62.