BIX looks at four target dimensions which are identical for public and academic libraries: services, usage, efficiency and development.
The target dimension services consists of 5-6 indicators. They describe the infrastructure and services offered by the library to its users on the basis of the resources provided the funding institution. This includes e.g. staff, floor space, media budget, electronic services, library programmes and opening hours.
The usage dimension shows how the resources are put to work and how patrons use the services provided. High usage figures indicate that user needs have been met and adequate services are being offered.
Indicators in this dimension include the number of library visits (physical and virtual), the number of loans and stock turnover (public libraries) or the immediate availability of media and the attendance of library courses (academic libraries).
The efficiency dimension is the link between services offered and usage achieved. Libraries have to use their resources to maximize the benefit gained by their users and their funding institution. This also implies that good library services have their price. A "cheap" library need not necessarily be a "good" library.
Comparison of financial data is difficult in Germany because of widely varying accounting systems between federal states and local authorities.
Indicators include the costs per visit / per user, the ratio of resources allocated directly to user services, the ratio of acquisitions budget to loans. Academic libraries also measure the productivity of their media processing workflow and the circulation workflow.
Libraries must be able to adopt to continual change. This dimension contains indicators that monitor this ability.
This is mainly the quota of staff time devoted to professional development. For public libraries it also includes the amount of capital expediture and the stock renewal rate. For academic libraries it comprises the quota of university spending allocated to the library and the amount of third-party funding, as well as the percentage of staff capacity used for electronic services.