  The Galactic secondary cosmic ray anti-proton flux calculated with different
propagation models is fairly consistent with data, and the associated
propagation uncertainty is small. This is not the case for any anti-proton
exotic component of the dark matter halo. Detailed propagation models are
mandatory if the ultimate goal is to explain an excess. However, simpler and
faster approximate formulae for anti-protons are an attractive alternative to
quickly check that a given dark matter model is not inconsistent with the
anti-proton observed flux. This paper provides such formulae. In addition, they
could be used to put constraints on new physics in this channel, where an
extensive scan of a large parameter space could otherwise be quite expensive in
computer ressources.
