Comparison of Dewey and Library of Congress subject classification

This is a conversion chart showing how the Dewey Decimal and Library of Congress Classification systems organize resources by concept, in part for the purpose of assigning . These two systems account for over 95% of the classification in United States libraries, and are used widely around the world.
The chart includes all ninety-nine second level (two-digit) DDC classes (040 is not assigned), and should include all second level (two-digit) LCC classes. Where a class in one system maps to several classes in other system, it will be listed multiple times (e.g. DDC class 551).
Additional information on these classification plans is available at: