A map of the system

Dewey Decimal Classification (DDC)

Dewey Decimal Classification, often called the Dewey Decimal System or DDC, is a system libraries use to organise materials by subject.

Choose the resource for your task

Find a book’s numberSearch catalogue records and check their sources.Get a printable overviewDownload a ten-class chart in A4 or US Letter.Learn to read and sortUnderstand decimal order and local call numbers.Explore the categoriesCompare the scope of the ten broad classes.

The system and the local library

DDC provides a shared classification structure. Individual catalogues and shelving practices still differ. A numeric classification can be recorded separately from an item’s full call number, collection or physical location.

DDC and other systems

Not every library uses Dewey. You may encounter Library of Congress Classification, a bookstore-style arrangement or local collection labels. This tool does not turn a shelf mark from another system into a Dewey number merely because both appear in a record.

Official schedules and independent lookup

OCLC maintains the official classification and WebDewey. This independent site uses available public bibliographic records. It is not a substitute for the full schedules or professional classification decisions. Our chart is an original learning overview, not the full official tables.

References and data methods

Read how we use catalogue data and what happens to a search.