For a professional benchmarking, it is necessary to split libraries into peer comparison groups.

For public libraries, this done according to the size of the community they serve. The size of the town / community determines the profile and task of libraries: in larger cities, they must be prepared to serve specialized and in-depth information needs. On the other side, some input values can not be scaled down in very small communities - a minimum of floor space, media and staff must be available even in the smallest village. Libraries in small towns and villages therefore may have higher service indicator values than those in middle or large sized cities.

In order to give BIX-participants additional information for the strategic development of their libraries, the BIX-database includes a reference to the demographic type of the parent community according to the information system "Wegweiser Kommune" of the Bertelsmann Foundation. The demographic type does not have any effect on the BIX results.