  The AGN bolometric correction is a key element to understand BH demographics
and compute accurate BH accretion histories from AGN luminosities. However,
current estimates still differ from each other by up to a factor of two to
three, and rely on extrapolations at the lowest and highest luminosities. Here
we revisit this fundamental issue presenting general hard X-ray ($K_{X}$) and
optical ($K_{O}$) bolometric corrections, computed combining several AGN
samples spanning the widest (about 7 dex) luminosity range ever used for this
kind of studies. We analysed a total of $\sim 1000$ type 1 and type 2 AGN for
which a dedicated SED-fitting has been carried out. We provide a bolometric
correction separately for type 1 and type 2 AGN; the two bolometric corrections
results to be in agreement in the overlapping luminosity range and therefore,
for the first time, a universal bolometric correction for the whole AGN sample
(both type 1 and type 2) has been computed. We found that $K_{X}$ is fairly
constant at $log(L_{BOL}/L_{\odot}) < 11$, while it increases up to about one
order of magnitude at $log(L_{BOL}/L_{\odot}) \sim 14.5$. A similar increasing
trend has been observed when its dependence on either the Eddington ratio or
the BH mass is considered, while no dependence on redshift up to $z\sim3.5$ has
been found. On the contrary, the optical bolometric correction appears to be
fairly constant (i.e. $K_{O} \sim 5$) whatever is the independent variable. We
also verified that our bolometric corrections correctly predict the AGN
bolometric luminosity functions. According to this analysis, our bolometric
corrections can be applied to the whole AGN population in a wide range of
luminosity and redshift.
