Distributions of ΔRfree for 1195 X-ray structures from the PDB with a reported resolution of 2.00 Å. ΔRfree = Rfree, org − Rfree, recalc, where Rfree, org values were taken from the PDB-file headers and Rfree, recalc values were recalculated after subsequent refinement steps: (i) simple recalculation of Rfree without any additional refinement, (ii) rigid-body refinement to compensate for any accidental translation or rotation of the coordinates before deposition and (iii) refinement with TLS models for atomic displacement. TLS models in PDB headers were kept if available; in all other cases one group per chain was used. The Gaussian fits through these histograms are for visual reference only. The average Rfree values reported in the PDB are 24.2%. We recalculated these values without additional refinement and obtained an average of 24.5%. After rigid-body refinement and TLS refinement, the average Rfree values were 24.3% and 23.0%, respectively.