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UMass Amherst Libraries

Patents and Trademarks

Patent Classification - What you need to know before you begin

Patent classification systems are used to organize all inventions into similar groupings - putting like with like.

The USPTO created the USPC (United States Patent Classification) system over time to where it now contains approximately 450 classes and 150,000 subclasses.

Use the Index to U.S. Patent Classification (USPC) System to help find the correct patent classification. 

Beginning 1 January 2015 the USPTO starting the process of switching over to using the CPC (Cooperative Patent Classification) system.  This change is due in part to the globalization of patents and people wanting to search cross patent systems. 

As U.S. patents work their way through the application and granting phases, both systems (USPC and CPC) should be searched.


Determining the classification of an invention is by far the hardest part of the patent search process.

U.S. Patent Classification Systems

Legacy USPC system (no longer updated)

USPC (United States Patent Classification)

USPC Class Numbers and Titles

Index to USPC Patent Classification

New CPC system

CPC (Cooperative Patent Classification)

Classification Searching - How to get started

To determine if an invention has been patented a thorough patent search should be conducted.  This will entail searching a number of different patent websites, so it is wise to keep a journal of your work as to not duplicate efforts.

In general:

1.  Brainstorm Keywords to describe your invention - think of synonyms.

2.  Use Keywords to search for a similar match of your invention in Google Patents.

3.  Note the class and subclass of the similar invention - either in USPC or CPC, or both.

4.  Use the class and subclass to search patents and patent applications at the USPTO website classification or the Espacenet databases.

5.  Trace related patents through references.

Detailed Seven Step Search Strategy from the USPTO (pdf, 2015)

Although Google Patents is easier to use it is not as up to date as the USPTO website.