How to Search for a Patent by Patent Number

If you already have a patent number, finding the corresponding patent can be much easier than starting a search from scratch.

The U.S. Patent and Trademark Office (USPTO) provides a free tool called Patent Public Search that lets you look up U.S. patents and published patent applications by number. You can also use Google Patents to quickly locate a patent and review its information.

This guide explains how to search for a patent by patent number, what different patent numbers mean, and what to look at once you find the document.

Quick Answer: How Do You Search for a Patent by Number?

The easiest way is to use the USPTO's Patent Public Search tool.

Enter the patent number or published patent application number into the Quick Lookup field and select Search.

You can also search the number in Google Patents, which can be useful for quickly finding the patent document and exploring related patents.

If you already know the number, you generally do not need to search by keywords or inventor name first.

What Is a Patent Number?

A patent number is an identifier assigned to an issued U.S. patent.

For example, a utility patent might have a number such as 9,204,578. When searching the USPTO database, the number may need to be entered without commas and with leading zeros depending on its length and the search field being used.

Different types of patent documents can use different numbering systems, so it is important to know what kind of number you have before searching.

Patent Number vs. Publication Number

One of the easiest ways to get confused when searching for a patent is assuming that every number associated with a patent application is the same thing.

They are not.

Patent number

A patent number identifies an issued U.S. patent.

For example:

9,204,578

This type of number is associated with a patent that has been granted.

Published patent application number

A published U.S. patent application has a different number format from an issued patent.

Published patent application numbers contain the four-digit publication year followed by seven additional digits. For example:

20210123456

When using the USPTO's Patent Public Search Quick Lookup, enter the publication number as an 11-digit number without the slash.

For example:

2021/0123456 → 20210123456

Application number

A patent application also has an application number assigned to it during the filing process.

An application number is different from both the patent number and the published patent application number.

If you are trying to find a particular patent document, make sure you know which number you actually have.

How to Search for a Patent Number Using the USPTO

The USPTO's Patent Public Search tool is the best place to start when you want to search the official U.S. patent records.

Step 1: Open Patent Public Search

Go to the USPTO's Patent Public Search tool.

The Basic Search interface is designed to make common patent searches easier, including searches using patent or publication numbers.

Step 2: Find Quick Lookup

At the top of the Basic Search interface, look for the field labeled:

Patent or Publication number

This is the Quick Lookup option.

Step 3: Enter the Number

Enter the patent number or published patent application number you want to find.

For example, you might enter:

9204578

The USPTO notes that patent numbers with six digits or fewer should be entered with leading zeros to create a seven-digit number in the Quick Lookup system.

You generally do not need to include commas.

The USPTO notes that patent numbers with six digits or fewer should be entered with leading zeros to create a seven-digit number in the Quick Lookup system.

For example:

123456 → 0123456

More recently issued utility patents can have eight-digit numbers, so those numbers should be entered as provided.

For published patent applications, use the complete 11-digit publication number, including the four-digit publication year and seven additional digits. Do not include the slash.

Step 4: Select Search

Select Search.

If the number is valid and matches a document in the database, Patent Public Search should return the corresponding patent or published application.

From there, you can open the document and review its information.

How to Search for a Design Patent by Number

Design patents use a slightly different numbering format.

A design patent number includes a D before the number.

For example:

D123456

The USPTO's search documentation explains that the D prefix takes the place of a digit when formatting a design patent number for Quick Lookup.

This means that if you are searching for a design patent, do not leave out the D.

The same principle applies to plant patents, which use a PP prefix.

How to Search for a Patent Number Using Google Patents

Google Patents provides another convenient way to find a patent.

Go to Google Patents and enter the patent number into the search field.

For example:

9204578

You can also search using a patent publication number.

Google Patents may be particularly useful when you want to quickly review the patent's title, inventors, filing information, drawings, claims, and related documents.

However, when you need to verify information against the official U.S. patent record, the USPTO's Patent Public Search is an important source to check.

What Can You Learn From a Patent You Find?

Finding the patent is only the beginning.

Once you locate the document, there is a lot of useful information you can examine.

Patent title

The title gives you a quick description of the subject matter covered by the patent.

Keep in mind that the title is not necessarily a complete description of what the patent protects.

Inventor names

The patent will identify the inventors associated with the invention.

You can use those names to continue your research.

For example, if you find an interesting patent and want to see what else the same inventor has patented, you can search by inventor name.

Learn more:

How to Search for a Patent by Inventor Name

Assignee or owner information

Patent records may also contain information about the assignee.

An assignee is generally the party to which rights in the patent have been assigned.

This can help you understand who owns or has owned rights associated with the patent, although ownership information can change over time.

Filing and publication dates

The patent record can show important dates associated with the application and patent.

These dates can help you understand when the application was filed, when it was published, and when a patent was granted.

Patent drawings

Drawings can provide a quick visual understanding of the invention.

For many patents, the drawings make it much easier to understand how the invention is constructed or how its components relate to one another.

Claims

The claims are particularly important because they define the scope of the patent rights.

Do not assume that everything described or shown in a patent is necessarily covered by the claims.

If you are trying to understand what a particular patent actually protects, the claims deserve careful attention.

What If the Patent Number Does Not Work?

There are several reasons a patent number search might not return the result you expected.

Check the number

Make sure you entered the number correctly.

A single missing or incorrect digit can prevent the search from finding the document.

Remove commas

When using the USPTO search interface, try entering the number without commas.

For example:

9,204,578

becomes:

9204578

Check for a prefix

If you are searching for a design patent, make sure you include the D prefix.

For a plant patent, check whether the PP prefix is required.

Check whether you have a publication number

If the number begins with a year, such as 2021, you may be looking at a published patent application rather than an issued patent.

Try entering it as a publication number rather than assuming it is a patent number.

Try Google Patents

If you are having trouble with the USPTO interface, searching the number in Google Patents can sometimes make it easier to identify the document.

Once you find the document, you can then verify the information using the USPTO.

How to Use a Patent Number to Continue Your Search

Finding one patent can give you several new ways to expand your research.

For example, you might find a patent and then search for:

• Other patents by the same inventor

• Other patents assigned to the same company

• Earlier patents cited by the document

• Later patents that cite the document

• Similar patents using related terminology

• Patents in the same classification

This is one reason patent searching is often an iterative process.

You may start with one patent number and use the information inside that patent to discover many more relevant documents.

Patent Number Search vs. Keyword Search

Searching by patent number and searching by keywords serve different purposes.

Patent number search is useful when you already know which document you want to find.

Keyword search is useful when you are trying to discover patents related to a particular invention, technology, or concept.

If you already have a patent number, searching by number is usually the fastest way to locate that specific document.

If you are trying to determine whether similar inventions already exist, a broader patent search is more appropriate.

Learn more:

How to Do a Patent Search: A Step-by-Step Guide for Inventors

Common Mistakes When Searching by Patent Number

Confusing the patent number with the application number

These numbers identify different things. Make sure you know which number you have before searching.

Leaving out a design patent prefix

A design patent number includes a D prefix. Leaving it out can cause problems when searching.

Including commas

When using the USPTO search interface, enter the number in the format expected by the search field rather than simply copying a formatted number with commas.

Assuming one patent tells the whole story

A patent can lead you to related patents, earlier prior art, later improvements, and other documents.

Use the patent you find as a starting point for additional research when appropriate.

Assuming a patent is still active

Finding a patent record does not automatically tell you that the patent is currently enforceable.

Patent status can depend on the specific patent, maintenance requirements, expiration rules, assignments, and other factors.

If current legal status matters, use the appropriate USPTO records and consider getting professional advice.

Frequently Asked Questions

Can I search for a patent using only the patent number?

Yes. The USPTO Patent Public Search Basic interface provides a Quick Lookup option specifically for patent or publication numbers.

Can I search for a patent by publication number?

Yes. The USPTO Patent Public Search tool supports searches for published U.S. patent applications as well as issued patents.

Can I search for a design patent by number?

Yes. Design patents can be searched by their patent number, including the D prefix.

Can I find an old patent by its number?

Yes. The USPTO's patent search system includes U.S. patent records going back many years, although the amount of searchable information available can vary for older documents.

Can I find the inventor from a patent number?

Yes. Once you locate the patent, the patent record will identify the listed inventors.

You can then use that information to search for other patents associated with the inventor.

Does finding a patent mean the patent is still active?

No. A patent record may remain available even after the patent has expired or otherwise ceased to have enforceable rights.

If current patent status matters, check the appropriate USPTO records rather than assuming a patent is active simply because you can find it.

Final Thoughts

If you already have a patent number, you do not need to start with a complicated patent search.

The USPTO's Patent Public Search tool provides a Quick Lookup option for patent and published application numbers, making it possible to locate a specific U.S. patent or publication directly.

Once you find the document, however, there is much more you can learn from it. The inventors, assignee, dates, drawings, claims, citations, and related documents can all provide useful information for continuing your research.

A single patent number can therefore be more than a way to find one document. It can be the starting point for a much broader patent search.

Continue Learning

Want to learn more about searching patents?

How Do I Search Existing Patents?

How to Do a Patent Search: A Step-by-Step Guide for Inventors

How to Search for a Patent by Inventor Name

Patent Basics

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