Key Takeaways

  • Patent application numbers, publication numbers, and patent numbers serve distinct roles in tracking an invention through its lifecycle.
  • A publication number identifies the published application and is different from both the application number and the final patent number.
  • Publication numbers help the public find and review pending applications once they are made available (typically 18 months after filing).
  • International applications (WO patents under the Patent Cooperation Treaty) also receive unique publication numbers for global tracking.
  • Understanding the distinction between these identifiers ensures inventors, businesses, and researchers cite and reference the correct number when discussing patents.

Patent Application Number Versus Publication Number

Also called the patent's serial number, patent applications all receive an application number from the U.S. Patent and Trademark Office (USPTO). If the application is approved and the invention is officially patented, the patent will have a full patent number.

Application numbers follow this format: XX/XXX,XXX with a forward slash after the first two digits. The full patent number follows this format: X,XXX,XXX. If a patent is published, it will also receive a publication number with the following format XXXX/XXXXXXX.

On an official U.S. patent cover, the format of the patent number would also have a letter and number at the end, for example: US 7,493,599 C2.

Why Publication Numbers Matter

A publication number is more than just an identifier—it plays a key role in how the public, researchers, and competitors access information about a pending invention. Once published, the application is indexed by its publication number and becomes searchable in the USPTO database and international patent databases. This makes it easier for third parties to evaluate the state of the art, assess potential licensing opportunities, or avoid infringing on new technologies. Unlike the application number, which is mainly used by the USPTO to track filings internally, the publication number serves as the public-facing reference point.

Publication numbers also serve legal and academic functions. For instance, they are often used in legal proceedings to establish prior art or to check the timeline of an invention’s development. Academics and industry professionals may cite a publication number when discussing emerging technologies, ensuring readers can locate the exact document referenced.

What Is a Patent Publication?

A patent publication looks similar to the patent itself, but they also reflect the original patent application document. The publication number, notes the year of publication. For a patent that has the publication number 2013/9304893, its publication is the year 2013. The seven-digit number after the forward slash is unique and doesn't reflect the patent or application number. The purpose of all of these different numbers is to keep the many patents in their different stages well-organized. The U.S. Patent Office (USPTO) assigns these numbers as they choose.

Not every patent application is published, some inventors may choose to not have their application published. This is an option during the original filing of the application. If the box for not publishing the application is left unchecked, the USPTO will publish the application 18 months after the application is filed.

Once a patent application is published, a PDF version of the application and the filed documents will be made available. On the patent publication date, the patent becomes publicly available and no longer confidential. This means that anyone who searches for the patent can read its specifications and claims and can keep up with the status of the patent to see when it is officially granted by the State.

Patents haven't always been published, but the American Inventors Act of 1999 started the publication practice with the first patent application published in 2001. Before patent applications were published, people couldn't learn about patents until they were officially issued. Even though the publication of patents is very common, some inventors do choose to forego this part of the process and kept their patents a secret until they're issued.

If your patent is in the process of being approved but hasn't been published, it's a bad idea to include your application number on a resume or any other public document. When you include the application number on a document, it is basically useless if the patent application isn't published because no one can view it.

Publication Number Format and Examples

Publication numbers follow a standardized format to make them easy to distinguish from application and granted patent numbers. In the United States, they appear as US YYYY/XXXXXXX A1, where:

  • US identifies the issuing office.
  • YYYY indicates the year of publication.
  • XXXXXXX is the unique serial assigned to the published application.
  • A1, A2, etc. designate the kind code, which signals whether the publication is the first or a corrected version.

For example, US 2019/0123456 A1 refers to a patent application published in 2019. The “A1” tells us it is the first publication of that application. These identifiers are consistent across many jurisdictions, though the prefixes and codes vary. The European Patent Office, for instance, uses the prefix “EP,” while WIPO uses “WO” for Patent Cooperation Treaty applications.

Because publication numbers are universally recognized, they make it possible to trace related applications across borders, which is especially important for inventors filing in multiple jurisdictions.

What Is a WO Patent?

The World Intellectual Property Organization (WIPO) grants WO patents. Patent law protects these types of patents across all countries in the United Nations. For patents to receive protection beyond just the United States, or whichever country the patent is in, it is more complicated and expensive to obtain individual patents in each country. The WO patent is a great option for countries that want to expand and have their patents recognized internationally.

The Patent Cooperation Treaty is kept in practice by the WIPO. This treaty provides a simpler process for inventors to follow in order to file patent applications over the countries that participate in the treaty. The U.S., China, and some European countries are part of the Patent Cooperation Treaty making up a total of 184 countries that are members of the group.

WIPO offers several helpful tools for inventors hoping to obtain a patent. This organization can provide advice and information about invention patentability and requirements.

Filing a patent application in one of the states that are members of the WIPO and the Patent Cooperation Treaty, gives the patent an automatic preservation for one year for filing in any of the other states that are also members. This allows people a chance to apply for patents one at a time in multiple countries.

Application Numbers vs Publication Numbers in International Context

In international filings, the difference between application and publication numbers becomes even more significant. When an inventor files through the Patent Cooperation Treaty (PCT), the application receives a unique international application number and, once published, a WO publication number (for example, WO 2020/045678). These identifiers are crucial because national patent offices use them to track corresponding applications that enter their jurisdictions.

Publication numbers in this context serve as the central reference point for accessing documents in the WIPO PATENTSCOPE database, ensuring transparency across 150+ jurisdictions. By contrast, application numbers are usually confined to the office where the application was first filed. Understanding these distinctions is key for inventors seeking protection in multiple countries and for businesses monitoring competitor activity worldwide.

Frequently Asked Questions

  1. What is the difference between a patent application number and a publication number?
    A patent application number is assigned upon filing, while a publication number is issued when the application is made public, typically 18 months later.
  2. Does every patent application receive a publication number?
    No. Applicants can request non-publication when filing. If this request is not made, the USPTO automatically assigns a publication number once the application is published.
  3. How can I use a publication number to find a patent application?
    You can search the USPTO’s Patent Application Information Retrieval (PAIR) system or global databases like WIPO’s PATENTSCOPE using the publication number.
  4. Are publication numbers the same worldwide?
    No. Each jurisdiction uses different prefixes and formats (e.g., US, EP, WO), but all serve the same purpose of uniquely identifying a published application.
  5. Why are publication numbers important in legal disputes?
    Publication numbers are often cited as evidence of prior art or used to establish timelines in patent litigation, making them legally significant identifiers.

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