We analyze quantitatively the tuning of composite Higgs models with partial
compositeness and its interplay with the predicted Higgs mass. In this respect
we identify three classes of models, characterized by different quantum numbers
of the fermionic colored resonances associated with the top quark, the
so-called top partners. The main result of this classification is that in all
models with moderate tuning a light Higgs, of 125 GeV mass, requires the
presence of light top partners, around 1 TeV. The minimal tuning is comparable
to the one of the most attractive supersymmetric models in particular the ones
realizing Natural SUSY. This gives further support to an extensive program of
top partners searches at the LHC that can already probe the natural region of
composite Higgs models.Comment: 32 pages, 14 figures; v2: version published in JHE