  The idea that new physics could take the form of feebly interacting particles
(FIPs) - particles with a mass below the electroweak scale, but which may have
evaded detection due to their tiny couplings or very long lifetime - has gained
a lot of traction in the last decade, and numerous experiments have been
proposed to search for such particles. It is important, and now very timely, to
consistently compare the potential of these experiments for exploring the
parameter space of various well-motivated FIPs. The present paper addresses
this pressing issue by presenting an open-source tool to estimate the
sensitivity of many experiments - located at Fermilab or the CERN's SPS, LHC,
and FCC-hh - to various models of FIPs in a unified way: the Mathematica-based
code SensCalc.
