What Is the Dewey Decimal Classification System?

The Dewey Decimal Classification (DDC) is the world’s most widely used library classification system. Developed by Melvil Dewey in 1876, DDC organizes library materials by subject using a hierarchical decimal numbering system. Over 200,000 libraries in at least 135 countries use DDC to arrange their collections.

How Dewey Decimal Works

The Ten Main Classes

DDC divides all knowledge into 10 main classes, each represented by the first digit (0-9):

The Decimal Structure

Each main class subdivides into more specific topics using decimals:

500 - Science
  510 - Mathematics
    516 - Geometry
      516.3 - Analytic geometry
        516.35 - Algebraic geometry
          516.352 - Plane curves

This hierarchical system allows infinite precision while maintaining browsability.

DDC Call Number Components

A complete Dewey call number typically includes:

1. Classification Number

The DDC number from the schedules (e.g., 641.5 for Cooking)

2. Cutter Number

Letters/numbers representing the author’s last name or title:

• Based on the Cutter-Sanborn table
• Example: “S655” for “Smith, Jane”

3. Additional Elements (optional)

• Publication year
• Volume number
• Copy number
• Edition

Example Call Number:

641.5        ← DDC number (Cooking)
S655c        ← Cutter for Smith, Jane + title initial
2023         ← Publication year

Why Libraries Use Dewey Decimal

1. Intuitive Browsing

Related subjects sit together on the shelf. Someone looking for a book on Italian cooking (641.5945) will find all Italian cookbooks nearby.

2. Universal Standard

DDC is used worldwide, making it easier to:

• Share bibliographic records
• Train staff who move between libraries
• Understand other libraries’ systems

3. Continuously Updated

Now in its 23rd edition, DDC evolves to accommodate new subjects:

• Computer science expanded from a subsection to major coverage
• LGBTQ+ topics received dedicated numbers
• Environmental sciences reorganized to reflect modern understanding

4. Relative Index

DDC’s extensive index provides multiple access points to find the right number for interdisciplinary topics.

5. Practical for Most Libraries

Simpler than Library of Congress Classification, making DDC ideal for:

• Public libraries
• School libraries
• Small academic libraries
• Special libraries with general collections

DDC in Koha Library System

Configuring DDC in Koha

1. Classification Sources Navigate to Administration → Classification Sources

• Set “Dewey Decimal Classification” as default
• Configure classification split rules for labels

2. Cataloging Frameworks In MARC framework for field 082 (DDC number):

• Make visible and editable
• Enable plugin for browsing schedules
• Set validation rules

3. Call Number Preferences Configure item-level call numbers:

• Use 082$a for classification number
• Generate Cutter numbers automatically or manually
• Add year, volume, copy as needed

Using DDC in Koha Cataloging

When cataloging with Dewey in Koha:

MARC Field 082 - Dewey Decimal Classification Number

082 04 $a 641.5945 $2 23

• Indicator 1: Type of edition (0=Full, 1=Abridged)
• Indicator 2: Source of number (4=assigned by agency)
• $a: Classification number
• $2: Edition number

Item Call Number (Field 952$o):

641.5945 S655c 2023

Spine Label Printing

Koha can generate spine labels from DDC call numbers:

• Tools → Label creator
• Template includes classification + Cutter
• Prints on Avery-compatible label sheets

Dewey Decimal Resources

Official Resources

• WebDewey - Online version with full schedules (subscription required)
• Abridged Dewey - Simplified version for small libraries
• Dewey Services - Training, updates, and support from OCLC

Free Tools

• Classify - OCLC’s free tool to search for DDC numbers by ISBN/title
• Library of Congress Catalog - Most LC records include DDC numbers
• Dewey.info - Introduction and summaries

In Koha

• Z39.50 import from Library of Congress (includes 082 field)
• Dewey number plugins for quick lookup
• Classification browser add-ons

Common DDC Cataloging Challenges

1. Choosing the Right Number

Many topics fit multiple locations. For example, “Computer programming for children”:

• 005.1 (Programming)
• 371.33 (Educational technology)
• 649.68 (Child rearing - educational activities)

Solution: Use DDC Manual and follow library policy for interdisciplinary works.

2. Keeping Numbers Updated

DDC evolves with new editions. Old numbers may become obsolete or relocated.

Solution: Don’t reclassify entire collection with each edition; maintain consistency unless numbers are egregiously outdated.

3. Local Variations

Libraries often adapt DDC to local needs:

• Expanding local history sections
• Creating special numbers for genres (mysteries, westerns)
• Condensing little-used classes

Solution: Document all local practices in a policy manual.

4. Long Numbers

Precise classification can yield unwieldy numbers (e.g., 641.5945632 for Venetian seafood cookbooks).

Solution: Truncate to practical length (most public libraries stop at 3-4 decimal places).

Dewey vs. Library of Congress Classification

Practical Tips for DDC in Koha

1. Import LC Records - Use Z39.50 to get professional DDC assignments
2. Use Classify - Free tool to find consensus DDC numbers for your materials
3. Be Consistent - Don’t agonize over perfect numbers; consistency matters more
4. Document Local Practice - Create a shelf list or authority file of assigned numbers
5. Train Thoroughly - Ensure all catalogers understand DDC principles
6. Use Cutter Tables - Standardize author/title Cutter numbers
7. Print Summaries - Keep DDC hundred/thousand summaries at cataloging stations

Example DDC Numbers by Topic

• 004.16 - Personal computers
• 133.3 - Paranormal phenomena
• 362.29 - Substance abuse
• 598.072 - Bird watching
• 613.2 - Dietetics and nutrition
• 641.5 - Cooking
• 741.5 - Comic books and graphic novels
• 791.43 - Motion pictures
• 823 - English fiction
• 973 - United States history

Conclusion

The Dewey Decimal Classification remains the most practical classification system for most libraries. Its logical decimal structure, broad adoption, and continuous updates make it an excellent choice for organizing collections in Koha.

While DDC has limitations—proprietary licensing, U.S.-centric biases in some areas, and complexity for very specialized collections—its benefits outweigh drawbacks for public, school, and small academic libraries.

Koha’s robust support for DDC, including MARC field handling, label printing, and integration with external tools, makes it easy to implement Dewey-based classification in your library.

Need help implementing or migrating to Dewey Decimal in Koha? Our team provides classification consulting and record cleanup services. Contact us to learn more.