The morphological classification of NGC 4123 is SBx(rs)ab, which indicates this is a spiral galaxy with a central X-shaped bar (SBx) encircled by an incomplete ring structure (rs) and moderate to tightly wound spiral arms (ab). The plane of the galaxy is inclined at an angle of 46.9° to the line of sight from the Earth. It lacks a large spheroidal bulge at the core, showing only a luminous point-like source.[10] Blue knots in the outer spiral arms indicate that star formation is ongoing.[7] The galaxy has a stellar mass of 1.95×1010M☉[6] with a star formation rate of 3.429±3.281 M☉·yr−1.[12] The atomic gas in the galaxy has a mass of 1.06×1010M☉.[10]
Weiner, B. J.; et al. (1996), Buta, R.; et al. (eds.), "Fabry-Perot Observations and Hydrodynamical Simulations of the Barred Spiral NGC 4123", Barred galaxies; Proceedings of a conference held at the University of Alabama; Tuscaloosa; Alabama; 30 May - 3 June 1995, Astronomical Society of the Pacific Conference Series, vol. 91, San Francisco: Astronomical Society of the Pacific, p. 489, Bibcode:1996ASPC...91..489W.