New black hole mass estimates are presented for a sample of 72 active galactic nuclei (AGNs) covering three decades in optical luminosity. Using a subsample of Seyfert galaxies, which have black hole mass estimates from both reverberation mapping and stellar velocity dispersions, we investigate the geometry of the AGNs’ broad-line region. It is demonstrated that a model in which the orbits of the line-emitting material have a flattened geometry is favoured over randomly-orientated orbits. Using this model we investigate the Mbh–Lbulge relation for a combined 90-object sample consisting of the AGNs plus a sample of 18 nearby inactive elliptical galaxies with dynamical black hole mass measurements. It is found that, for all reasonable mass-to-light ratios, the Mbh–Lbulge relation is equivalent to a linear scaling between bulge and black hole mass. The best-fitting normalization of the Mbh–Mbulge relation is found to be Mbh=0.0012Mbulge, in agreement with recent black hole mass studies based on stellar velocity dispersions. Furthermore, the scatter around the Mbh–Lbulge relation for the full sample is found to be significantly smaller than has been previously reported (Δlog Mbh=0.39 dex). Finally, using the nearby inactive elliptical galaxy sample alone, it is shown that the scatter in the Mbh–Lbulge relation is only 0.33 dex, comparable with that of the Mbh–σ relation. These results indicate that reliable black hole mass estimates can be obtained for high redshift galaxies.