1. Patent Searching 101
2. U.S. Classifications
3. Patent Numbers
4. Assignee Searching
5. United States Patent and Trademark Office Resources

To conduct a patent search in the United States, contact the United States Patent and Trademark Office or USPTO. A patent keeps people and businesses who don't own an invention from making money on it. Patents support research, science, and inventions.

Patents have long been part of the country's history. Many of the colonies that eventually became the first 13 states granted patents. In 1790, the United States government created the Federal patent system to standardize patent applications in the country. That way, businesses that sell their products in more than one state still only need to apply for one patent.  The USPTO has a comprehensive database of all the patents issued in the country from 1790 to 1909. It contains:

  • Patent numbers
  • Current U.S. classifications
  • The names of patent holders, also called patentees
  • Patent filing dates
  • Locations

You can usually find images of patent documentation as well.

 With a patent search, you can look at information about existing inventions, also called prior art. That way, you can avoid infringing on a patent that belongs to another person or company. 

Patent Searching 101

Visit the United States Patent and Trademark Office's patent search page for preliminary patent searching. The search engine is easy to use, and you can find most information for free. There's also a help section with lots of tips about using the online search features.

You can use Free Patents Online or Google Patent Search to look for patents as well. Google Patent Search's database starts at U.S. Patent No. 1, so you can search for a variety of patents, including those filed before 1976. Most sites only list patents from after that year. Free Patents Online provides copies of patent documents as PDFs, so it's easy to find diagrams and images.

When you're using any of these websites, you can improve your search quality by starting with the Advanced Search Page's specification field. If you find so many patents with your keyword or keywords that you can't examine them individually, change your specification field search to make it narrower.

U.S. Classifications

As you read your search results, keep track of the patent numbers and identify the U.S. classification for the types of inventions you're searching for. After you read several U.S. classifications related to your invention, go back to the Advanced Search Page and complete a classification search.

For example, Classification 206/545 is for insulated beverage containers. Type “CCL/206/545” on the Advanced Search Page to see all patents with this classification. You can also make your search narrower by combining the classification with a keyword. Looking for a patent is like searching for a needle in a haystack, and you can save time and avoid mistakes by using a professional patent searcher. Most professionals only conduct classification searches, and they're more familiar with the classification system than inventors.

Patent Numbers

Patent numbers are often placed on manufactured objects or products, and collectors use them to find information about antiques and collectibles. For patents that were issued after 1975, use one of the search engines mentioned above. If the patent was issued before 1976, you can search for it on the USPTO website by patent number, issue date, and U.S. classification. You can also use Google Patent Advanced Search to search by patent number, assignee, inventor, topic, date, and classification number. When you get a search result, you can refine your search by issue date, publication date, patent office, filing status, and patent type.

Assignee Searching

The assignee is the individual or entity who owns a patent. To search for a person, type the full name with the last name first, then the first name and the middle initial. For companies, type the name or the part of the name that you know. You can also search for variations of a company's name. If the business has subsidiaries, make sure you search for the right one.

United States Patent and Trademark Office Resources

You can visit several pages on the USPTO website for more information about patents. Issued patents from 1789 to the present are available, and you can search for published applications filed after March 2001. There's also a brief guide to searching for patents called the 7 Step Search Strategy. Search for the status and history of issued patents or applications with the Patent Application Information System or PAIR.

If you need help with patent searches in the United States, you can post your legal need or post your job on UpCounsel's marketplace. UpCounsel accepts only the top 5 percent of lawyers to its site. Lawyers on UpCounsel come from law schools such as Harvard Law and Yale Law and average 14 years of legal experience, including work with or on behalf of companies like Google, Menlo Ventures, and Airbnb.