  We study a magnitude of possible over/underestimation of the actual gamma-ray
luminosity L_{actual} of a millisecond pulsar when using so-called pseudo
luminosity L_{pseudo} which is inferred from a phase-averaged flux. Both,
L_{actual} and L_{pseudo} are calculated with the numerical code thatmodels the
millisecond pulsar magnetospheric activity in the space charge limited flow
approximation with unscreened accelerating electric field. The behaviour of
L_{pseudo}/L_{actual} depending on viewing angle is analysed in the energy
bands corresponding to the operational energy bands of Fermi GST and H.E.S.S.
II.
