  If SUSY provides a solution to the hierarchy problem then supersymmetric
states should not be too heavy. This requirement is quantified by a fine tuning
measure that provides a quantitative test of SUSY as a solution to the
hierarchy problem. The measure is useful in correlating the impact of the
various experimental measurements relevant to the search for supersymmetry and
also in identifying the most sensitive measurements for testing SUSY. In this
paper we apply the measure to the CMSSM, computing it to two-loop order and
taking account of current experimental limits and the constraint on dark matter
abundance. Using this we determine the present limits on the CMSSM parameter
space and identify the measurements at the LHC that are most significant in
covering the remaining parameter space. Without imposing the LEP Higgs mass
bound we show that the smallest fine tuning (1:13) consistent with a relic
density within the WMAP bound corresponds to a Higgs mass of 114$\pm$2 GeV.
Fine tuning rises rapidly for heavier Higgs.
