 For large molecules, the R-factor usually ranges between 0.6 (when computed for a random model and against an experimental data set) and 0.2 (for example for a well refined macro-molecular model at a resolution of 2.5 Ångström).Small molecules (up to "ca".1000 atoms) usually form better-ordered crystals than large molecules, and thus it is possible to attain lower R-factors.