  Comparing solar and stellar brightness variations is hampered by the
difference in spectral passbands used in observations as well as by the
possible difference in the inclination of their rotation axes from the line of
sight. We calculate the rotational variability of the Sun as it would be
measured in passbands used for stellar observations. In particular, we consider
the filter systems used by the CoRoT, $Kepler$, TESS, and $Gaia$ space
missions. We also quantify the effect of the inclination of the rotation axis
on the solar rotational variability. We employ the Spectral And Total
Irradiance REconstructions (SATIRE) model to calculate solar brightness
variations in different filter systems as observed from the ecliptic plane. We
then combine the simulations of the surface distribution of the magnetic
features at different inclinations using a surface flux transport model (SFTM)
with the SATIRE calculations to compute the dependence of the variability on
the inclination. For an ecliptic-bound observer, the amplitude of the solar
rotational variability, as observed in the total solar irradiance (TSI) is 0.68
mmag (averaged over solar cycles 21-24). We obtained corresponding amplitudes
in the $Kepler$ (0.74 mmag), CoRoT (0.73 mmag), TESS (0.62 mmag), $Gaia~ $
(0.74 mmag), $Gaia~ G_{RP}$ (0.62 mmag), and ), $Gaia~ G_{BP}$ (0.86 mmag)
passbands. Decreasing the inclination of the rotation axis decreases the
rotational variability. For a sample of randomly inclined stars, the
variability is on average 15% lower in all filter systems considered in this
work. This almost compensates for the difference in the amplitudes of the
variability in TSI and $Kepler$ passbands, making the amplitudes derived from
the TSI records an ideal representation of the solar rotational variability for
comparison to $Kepler$ stars with unknown inclinations.
