How to Dewey-Classify a Small Library (Step-by-Step)

The Dewey Decimal Classification (DDC) is the most widely used system for organizing books in public, school, and church libraries. This guide explains how it works and how to apply it confidently, even if you have never cataloged a book before.

1. Understand the ten main classes

Dewey divides all knowledge into ten broad classes, each assigned a hundred-number range:

• 000 — Computer science, information & general works
• 100 — Philosophy & psychology
• 200 — Religion
• 300 — Social sciences
• 400 — Language
• 500 — Science
• 600 — Technology
• 700 — Arts & recreation
• 800 — Literature
• 900 — History & geography

2. Narrow down to the specific number

Each class is subdivided. For example, literature (800) breaks into American literature in English (810), then the novel form, producing a number like 813 for American fiction. A decimal extension (e.g. 813.52) pinpoints the period or sub-genre.

3. Add a cutter number for the author

The cutter number alphabetizes books that share the same classification. It is derived from the author's surname — for example, Fitzgerald becomes something like F553, often with a lowercase letter for the title (F553g for Gatsby).

4. Finish with the year (optional)

Many libraries append the publication year to distinguish editions, completing a three-line spine label: 813.52 / F553g / 2004.

5. Shelve in order

Books are shelved left to right, top to bottom, in ascending numeric then alphabetic order. Consistency is everything — the same book should always produce the same call number.