Distribution in the M–z plane of the Planck SZ cluster catalogue (open red circles; Planck Collaboration XXIX 2014) compared with those from SPT (black; Reichardt et al. 2013; Bleem et al. 2015) and ACT (green; Marriage et al. 2011; Hasselfield et al. 2013), MaDCoWS (yellow; Brodwin et al. 2015), and NORAS and REFLEX from the MCXC meta-catalogue (blue; Piffaretti et al. 2011 and references therein). Some clusters may appear several times as distinct points as a result of differences in the mass estimate between surveys. The black dotted lines show the Planck mass limit for the medium-deep survey zone at 20% completeness (as defined in Planck Collaboration XXIX 2014) for a redshift limit of z = 0.5.