  We present the equivalence between the Wilson flow and the stout smearing.
The similarity between these two methods was first pointed out by L\"uscher's
original paper on the Wilson flow. We first show the analytical equivalence of
two methods, which indicates that the finite stout smearing parameter induces
${\cal O}(a^2)$ correction. We secondly show that they remain equivalent in
numerical simulations within some numerical precision even with finite cutoffs
and stout smearing parameters by directly comparing the expectation values of
the action density and we shortly mention the use of the equivalence.
