Bolometric–to–X-ray correction vs. black hole mass. The black solid line and gray shaded area represent the relation and its 1σ dispersion found by Martocchia et al. (2017) for WISSH quasars, PG quasars, and XMM-COSMOS Seyfert 1s. The black dashed line shows a typical value of κbol,X = 20. Symbols and colors are the same as in Figure 3.