Mass estimate for the supermassive black hole in the Swift source Sw 164449+57, based on the assumption that the observed QPO frequency f_obs = 4.8(1 + z) mHz corresponds either to the radial epicyclic (solid line), f_obs = f_rad, or to the vertical epicyclic (dashed line), f_obs = f_ver, frequency, in accordance with the twin peak QPO 3:2 resonance model. For a comparison, we also show the mass estimate based on an assumption that f_obs = Ω_K/2π is the Keplerian frequency at ISCO (dash-dotted line).