Patent Classification
Patent classification is a system for organizing all U.S. patent documents and other technical documents into specific technology groupings based on common subject matter. On January 1, 2013, the USPTO moved from using the United States Patent Classification (USPC) system to the Cooperative Patent Classification (CPC) system, a jointly developed system with the European Patent Office (EPO). CPC has now been adopted by many countries throughout the world.
The Office of International Patent Cooperation (OIPC) Classification Division consists of three support areas created to support CPC policies, practices, and maintenance. Those areas being:
Classification Standards and Development
Classification Standards and Development (CSD)is responsible for administrating the classification standards and development of the Cooperative Patent Classification (CPC). CSD supports Technology Centers in developing and maintaining the patent classification systems searched by examiners and other stakeholders. CSD also contributes to the IP5 Working Group on Classification and International Patent Classification (IPC) system to enable searches of unified classification schemes that yield both US and foreign documents.
Classification Editorial Division
Classification Editorial Division (CED)is responsible for publishing revisions to the Cooperative Patent Classification (CPC) scheme. CED supports internal and external classification stakeholders in modification, organization, and maintenance of the CPC scheme. CED also updates numerous classification-related reference tools and documents accessible from USPTO’s Internet and intranet sites.
Classification Quality and International Coordination
The Classification Quality and International Coordination (CQIC) division is responsible for ensuring classification quality, formulating classification policy, and developing objective quality assurance metrics. CQIC supports internal and external stakeholders by providing classification training. CQIC also oversees the administration of the Cooperative Patent Classification (CPC) project and works with international partners on classification harmonization.
Search Patent Classification Systems
Cooperative Patent Classification (CPC) system
The Cooperative Patent Classification (CPC) effort is a joint partnership between the United States Patent and Trademark Office (USPTO) and the European Patent Office (EPO) where the Offices have agreed to harmonize their existing classification systems (European Classification (ECLA) and United States Patent Classification (USPC) respectively) and migrate towards a common classification scheme.
CPC resources:
- CPC scheme (The 2026.01 version of the CPC is now in force.)
- USPTO and EPO bi-lateral CPC informational site
- CPC schemes and definitions bulk data page
- CPC concordance page
- List of technical areas where Combination Sets are authorised for classification (updated 9 January 2026)
The CPC Notice of Changes and Editorial Corrections are the official record of change for the CPC system.
United States Classification (USPC) system
The USPC classification scheme presented is primarily for historical purposes. After the implementation of the Cooperative Patent Classification (CPC), only the plant and design classification material is updated within the USPC.
- Index to USPC
- Seven step strategy suggested by thePatent and Trademark Resource Center to find relevant classifications.
- USPC class numbers and titles
- Guides
- Special guides to USPC and IPC:Environmentally Sound Technologies (EST) Concordance
Documents and reports related to the USPC Manual of Classification
- Classes within the U.S. classification system arranged by related subject matter [PDF]
- Classes arranged in alphabetical order [PDF]
- Consolidated glossary of USPC terms
Classification Orders
The USPC classification scheme presented is primarily for historical purposes. After the implementation of the Cooperative Patent Classification (CPC), only the plant and design classification material is updated within the USPC.
- Index to USPC
- Seven step strategy suggested by the Patent and Trademark Resource Center to find relevant classifications.
- USPC class numbers and titles
- Guides
- Special guides to USPC and IPC: Environmentally Sound Technologies (EST) Concordance
Documents and reports related to the USPC Manual of Classification
- Classes within the U.S. classification system arranged by related subject matter [PDF]
- Classes arranged in alphabetical order [PDF]
- Consolidated glossary of USPC terms
Classification Orders
A Classification Order documents changes to the USPC which have occurred while maintaining the system over time. A Classification Order identifies Reclassification Project team members, USPC classifications abolished, USPC classifications established, new classification definitions and changes to existing classification definitions.
- Classification under reclass [PDF]
- Classes in the U.S. Patent Classification System - Dates Established
- Classification Orders
- Classification Order Index (COI)
- Classification Orders Archival Report [PDF]
Relationships between classifications and organizations
The Patent Technology Center Directors coordinate patent examination through Art Units. The term, Art Unit, refers to the group of professionals responsible for a cluster of related patent art. Art Units are currently identified by a four digit number, i.e., 1642.
- Classes arranged by Art Unit (CAAU) [PDF]*
- Classes arranged numerically with Art Unit and search room locations (CAN) [PDF]*
* Historic data will appear for some Art Units until 2023 data system transitions are completed. Additional questions about Art Units can be directed to thePatents Ombuds Office.
Lists of withdrawn USPTO patent publications
Classification resources
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