  This letter reports on a new procedure for the lattice spacing setting that
takes advantage of the very precise determination of the strong coupling in
Taylor scheme. Although it can be applied for the physical scale setting with
the experimental value of $\Lambda_{\overline{\rm MS}}$ as an input, the
procedure is particularly appropriate for relative "calibrations". The method
is here applied for simulations with four degenerate light quarks in the sea
and leads to prove that their physical scale is compatible with the same one
for simulations with two light and two heavy flavours.
