We provide three statistical model prescriptions for the bolometric corrections appropriate for B-type stars as a function of (i) T_eff_, (ii) T_eff_ and logg, and (iii) T_eff_, logg and [M/H]. These statistical models have been calculated for 27 different filters, including those of the Gaia space mission, and were derived based on two different grids of bolometric corrections assuming LTE and LTE+NLTE, respectively. Previous such work has mainly been limited to a single photometric passband without taking into account non-local thermodynamic equilibrium (NLTE) effects on the bolometric corrections. Using these statistical models, we calculate the luminosities of 34 slowly pulsating B-type (SPB) stars with available spectroscopic parameters, to place them in the Hertzsprung-Russell diagram and to compare their position to the theoretical SPB instability strip. We find that excluding NLTE effects has no significant effect on the derived luminosities for the temperature range 11500-21000K. We conclude that spectroscopic parameters are needed in order to achieve meaningful luminosities of B-type stars. The three prescriptions for the bolometric corrections are valid for any galactic B-type star with effective temperatures and surface gravities in the ranges 10000-30000K and 2.5-4.5dex, respectively, covering regimes below the Eddington limit.