Research Guides: Patent Resources on the Web and in the Engineering Library: Patent Classification

Classification Tools

Patents are tough to search using keywords because of the complex legal and technical language they contain. To help patent searchers, patent offices use classification systems to group similar technologies together. If you find the right class, you can find all of the inventions related to that type of technology, regardless of how they're described.

Cooperative Patent Classification (CPC)
CPC is the patent classification system that is currently used by the United States and the European Patent Office. Other countries may also move to this system in the future. CPC is based on the International Patent Classification (IPC) system, but features many more sub-categories for more precise searching.
CPC Search Tool
The CPC system is arranged hierarchically, with each additional digit or letter adding a layer of complexity. Espacenet's CPC browser is an excellent way of exploring (or searching) this system to find the right code for your invention.
International Patent Classification (IPC)
IPC is the patent classification system used most commonly by patent offices around the world.
United States Patent Classification (USPC)
USPC is the legacy system used by the United States Patent & Trademark Office until 2016. It is no longer in use, although it can still be searched in some databases.

Concordances:

CPC and IPC (PDF)
USPC and IPC (browse tool)
USPC and CPC (search tool)

Patent Resources on the Web and in the Engineering Library

Subject Guide

Intellectual Property Glossary

Classification Tools