Patent Searching 101: A Patent Search Tutorial

Inventors and entrepreneurs who are looking to cut costs frequently want to do their own search.  This is a wise first move, but you really need to be careful.  It is quite common for inventors to search and find nothing even when there are things that could and would be found by a professional searcher.  So while it makes sense to do your own search first, be careful relying on your own search to justify spending the thousands of dollars you will need to spend to ultimately obtain a patent.  In other words, nothing in this article should be interpreted as me suggesting that inventors can or should forgo a professional patent search.  There is simply no comparison between an inventor done patent search and a patent search done by a pro.  Having said that, every inventor should spend time searching and looking if for no other reason than to familiarize themselves with the prior art.  Of course, if you can find something that is too close on your own you save time and money and can move on to whatever invention/project is next.  For more on patent searches generally see US Patent Search FAQs  and Patent Searching 102: Using Public PAIR.

If you are going to do your own searching and find relevant patents you are going to need to learn some strategies, and also about the free tools that are available to you.  If you are going to do your own preliminary patent searching you will want to take a look at the United States Patent Office patent search page. A lot of information can be found free, and the system is not terribly difficult to use. There is also an excellent Help Section on the Patent Office website to educate inventors on how to use the online search features. There is also another excellent (and free) site that you should use when searching – Free Patents Online. Whenever I search I always use both the USPTO and Free Patents Online. Perhaps the best thing about Free Patents Online is that they provide copies of the actual PDF documents, which contain all the images. Using the images on the USPTO website to obtain these full text PDF documents that contain the images is cumbersome to say the least.

Free Patents Online is also normally much faster than the USPTO site as well. Having said that, I personally find the patent search engine of the Patent Office better. Nevertheless, when I find a relevant patent I go to Free Patents Online for the PDFs and to access related patents, which is much easier because everything at Free Patents Online is hyperlinked. So once you find a handful of relevant patents definitely go to Free Patents Online so you can easily jump back and forth and look at the patents that are cited in each relevant patent you find.  In other words, I suggest that you consider using the strengths of both the USPTO and Free Patents Online sites to make your searching easier.


Google has also offers Google Patent Search, which is lightening fast (unlike the USPTO online database), but it does not have that many search fields, which makes it extremely difficult to use to narrow down your search.  Thus, Google is probably best used initially because when you start a search you cast a net very wide.  As you start to want to look for specific things, perhaps in particular parts of patent applications, the Google tool is just not very useful.

Another thing you MUST know about when you use Google Patent Search is that there are also some holes in the database.  I have specifically looked for patents I know to exist and cannot always find them.  I have heard the same experience from other patent attorneys and agents.  Additionally, the most recent patents are not available on Google.  What this means is you cannot only rely on Google, but you still must use Google.  The Google database covers patents that are issued all the way back to US Patent No. 1.  This scope is much broader than either Free Patents or the USPTO .  So while you might not find everything, while it is difficult to specifically narrow your search, you still really need to check yourself using the Google database to see if there are old references that might be on point.

When using the USPTO search features, either at the USPTO website or on Free Patents Online, one trick to improve search quality is to start by using the Advanced Search Page and searching in the specification field. Lets say, for example, you are looking for patents that relate to insulated containers for carrying beverages. In order to do this you will first need to pick a term or phrase that might appear within the written description of issued patents. Following this example, you might try in the search box – SPEC/”insulating beverage container”. When this search was conducted (on March 16, 2012) the results returned a list of 25 patents issued since 1976 that have used that phrase. This points to the first problem encountered by doing your own patent search online at the USPTO. You can only do full text searching back to 1976. This is probably not too much of a concern for those operating in the high-tech sector, but important to known nonetheless.  The fact that you can only search going back to 1976 can be extremely detrimental if you have a mechanical invention or gadget.  It is not at all uncommon — in fact it is extremely common — for inventors in every generation to seek solutions for the same or similar problems, which leads to the same or similar solutions/inventions.

In this case there are not many to choose from. Many times, however, the list will contain hundreds or even thousands of patents depending upon the popularity of the term or phrase selected. For example, if you search “SPEC/thermos”, you will find hundreds of patents that use this word in the specification. In fact, at the time this sample search was conducted (March 16, 2012) no fewer than 970 US patents have the word “thermos” in the specification, and that is only for patents issued since 1976. So what should you do now? If you find too many patents, rework the specification field search. For example, if your search were “SPEC/thermos and SPEC/beverage” you get down to 200 US patents.  Ultimately, upon receiving manageable results, just click on several of the patents.  The key, however, is to start off broad and then narrow your way down to those that are the most likely relevant references.

Once you receive manageable results you need to read the patents and see which ones are relevant. Try various search terms to make sure you are covering all possible descriptions of the invention. Along the way, as you read the patents and identify related ones keep track of the numbers and identify the US classification that relates to the type of invention you are searching. Upon identifying several US classifications that seem to relate to your invention, return to the Advanced Search Page and do a classification search. For example, again following our example, you may notice that classification 206/545 seems relevant. As it turns out, this classification relates to special receptacles or packages with an insulating feature. See US Classes by Number & Title. Therefore, it would seem that patents within this classification are potentially highly relevant. So return to the Advanced Search Page text box and enter “CCL/206/545”.  This will search for all the patents classified in 206/545, which as of the time the search was conducted resulted in 144 US patents.  You can also add to a classification search to narrow.  For example, if you search “CCL/206/545 and SPEC/beverage”, you get down to 50 US patents.

Admittedly, becoming familiar with the intricacies of doing a quality US patent search on your own will take time. Also, when searching using the USPTO system there are a number of fields that are searchable through the Advanced Search Page, which means that there are any number of ways to begin to tackle any search. If you are a serial inventor it is probably worthwhile spending time becoming acquainted with this and other ways to search. Having said this, however, if you are not intimately familiar with both advanced searching techniques and the Patent Classification System, you are almost certainly going to miss what you are looking for in your own search. While it is advisable for every inventor to at least do a preliminary search on their own, it is not uncommon for inventors to do a search and find nothing. Every time I do a patent search I find patents that were findable in the Patent Office database, but not located by the inventor. Sometimes those patents are tangentially related, sometimes they are quite close and sometimes they are exactly what the customer has invented. This is no doubt caused by the fact that a patent search is akin to searching for a needle in a haystack.  That is why the best money you can spend is to hire a professional patent searcher.

Any successful search must use rely upon the Patent Classification System, and any successful search (in my opinion) should start out extremely broad to make sure that the proper US classifications are identified. While the classification system is helpful, never forget that patent are classified as the Patent Office sees fit. In order to identify the appropriate classification a broad search is necessary to make sure you familiarize yourself with how inventors and patent attorneys routinely characterize certain inventions, features, scientific principles and concepts. Only after you have a broad idea of all possible descriptions can you meaningfully search the classification systems. Having said this, let me acknowledge that some will disagree with this last statement. Frequently a patent classification search is the only type of search that is conducted by individuals who are professional patent searchers. It is important to realize, however, that a professional searcher only searches for a living and is far more familiar with the classification system than any inventor or even any patent attorney. I also want to point out that even if you think you are familiar enough with the classification system, you are not!

Take a look at this patent:

US Patent No. 6,619,810
Halloween treat carrier
Issued September 16, 2003

This invention, according to claim 1, is “a container having thereon a Halloween design, wherein the container and/or the Halloween design comprises a glow-in-the-dark material.” While this invention is outrageous and it is ridiculous that it was ever patented, that is not the point here. The point is with respect to the US classification for this patent. Prior to reading on, go to the US classification menu on the Patent Office website. Take some time and try and figure out what classification this invention would best be placed in. What you will find, I suspect, is that using the classification system in the first instance is at best cumbersome.

Now I invite you to review this patent – US Patent No. 6,619,810. Notice that the US classification for this patent is 362/84 and 362/156. Notice that 362/84 is in bold. This means that it is the primary US classification for this invention. If you look at class 362 you learn that the class is broadly titled “Illumination”. The subclass of 84 relates to “Light source or light source support and luminescent material.” The secondary subclass of 156 a container, specifically a “bag, purse or trunk”. When looking at this particular invention in the first instance how many would have thought that this invention would best be described as a light source support and/or as an invention related to illumination? Once you narrow down the proper class to illumination finding subclass 156 would not be difficult, and maybe even finding subclass 84 might be possible. The point with this exercise, however, is to illustrate that finding a classification number first is difficult if not impossible when you are engaging in patent searches infrequently. It is always more wise to broadly search, perhaps searching the specification (using SPEC/) and find somewhat relevant patents. Then with respect to the most relevant patents, make note of their US classification numbers and then search those numbers. The reason individual inventors do not find the most relevant patents is because they almost always fail to follow up the broad search with a classification search. In every patent search I can remember doing the most relevant patents were not discovered until I identified the most likely US classifications and did a classification search.

Also remember that it is critically important to figure out what things are called.  I cannot stress this enough.  You need to use different names and labels.  You will find that patent attorneys typically call certain features by a select few names.  These names are not always obvious, but once you figure out what the industry calls something you are far more likely to find relevant patents.

Good luck!


Warning & Disclaimer: The pages, articles and comments on do not constitute legal advice, nor do they create any attorney-client relationship. The articles published express the personal opinion and views of the author as of the time of publication and should not be attributed to the author’s employer, clients or the sponsors of

Join the Discussion

11 comments so far.

  • [Avatar for Gene Quinn]
    Gene Quinn
    February 10, 2014 04:57 pm


    I don’t know how you could have an invention stolen by someone watching trademark registrations. The name you are seeking even associated with a brief descriptions of the goods/services wouldn’t inform anyone of an inventive concept. FYI… you do need to be using the good/service in interstate commerce or else you would have to file an intent to use application.


  • [Avatar for Chase]
    February 10, 2014 04:07 pm

    Very informative. Thank you Gene. My concern is that I’ve there are hackers/thieves, etc., who watch the key words that are used to perform a search on Google, or the PTO, and they can steal your invention this way before you even get started. Is this true? Also, should I register a trademark before I submit a Prov Patent application, or do I stand the chance of getting my invention stolen by someone watching the new trademark registrations?

  • [Avatar for Bart van Wezenbeek]
    Bart van Wezenbeek
    January 4, 2013 11:17 am

    Like PS DIP I want to emphasize the use of Espacenet for (patent) prior art searching by the inventor. This for two reasons:
    1) soon the new AIA will enter into force and this means that prepublished prior art becomes more important than it was already. It will not be possible anymore to swear behind an earlier (foreign) application. Further, also PCT applications that are filed before your filed and that are not in the English language will become full prior art. These applications – as long as they are in the international phase – can not be found on the sites where only US documents are gathered.
    2) as has been said by PS DIP already: the espacenet collection is seven times as big as the US collection. Admiitedly, much of the information is in a language different from English. But – here comes the strength of the Espacenet system – there is a automatic translation available already for most of the languages in which the applications are published, even for Chinese. Thus, Espacenet enables to obtain patent information also from foreign languages.

    Thus, in conclusion, using only the USPTO site, Google patents and or Free patents Online equals fooling yourself by looking for your food only in one kitchen cupboard while there is a whole refrigerator filled with the stuff.

  • [Avatar for Mark Nowotarski]
    Mark Nowotarski
    March 31, 2012 12:29 pm


    The only place you can file a US patent application is with the USPTO. Here’s a link to their electronic filing system

    Here’s a link to the USPTO fee schedule

  • [Avatar for Craig Brown]
    Craig Brown
    March 30, 2012 07:07 pm

    I used to do internet searches related to technology, which often led to the description portion of patents that had been filed at the FreePatentsOnline (“FPO”) website. I just now signed up, and from what i can tall, there’s no provision for filing new patents – only searching for existing patents? (Is this tru, and if so, what changed, and why?)

    Assuming there ever was a way to file new patents, I’m curious how that worked. Unless FPO was recognized as some sort of a branch of the USPTO, all you were doing was publishing your ideas on a public forum, which I understood to mean they could no longer be patented.

    A quick response to the above would be very much appreciated, along with a fee schedule for (a) US Patents and (b) World Wide Patents.

    Thanks in advance,
    Craig Brown

  • [Avatar for Mark Nowotarski]
    Mark Nowotarski
    March 30, 2012 07:39 am

    Absolutely. A classic example is the light bulb. Thomas Edison didn’t have the first patent on it, Henry Woodward did (US 181,613). Edison’s patents were on improvements to the light bulb, such as light bulbs with thin carbon filaments. It was these improvements that led to commercial success.

  • [Avatar for patent idea]
    patent idea
    March 29, 2012 01:36 pm


    Thanks for making that important distinction. Many patented inventions are only protected on the specific function of the invention and not the entire idea of it. Inventors just need to realize that they should dig deeper before giving up.

  • [Avatar for Mark Nowotarski]
    Mark Nowotarski
    March 19, 2012 04:47 pm

    Good comments regarding confidentiality, but the USPTO search page can be a bit confusing if you are not used to it. Here’s a link to a recent article I wrote for the Insurance IP Bulletin on how to use the USPTO’s patent search page .

    Remember, the goal of a patent search isn’t to see if an invention is patentable, but to see what is patentable. All too often inventors get discouraged when they find something in an initial search that is similar to their idea. If they dive into the details, however, the truly novel and patentable features of the invention become apparent.

  • [Avatar for PS DIP]
    PS DIP
    March 19, 2012 11:05 am

    Leather and AC,

    I would strongly recommend using the EPO’s Espacenet site for some of your searching for two reasons. First, it has approximately 70 million patent documents in a single database as compared to the 10 million in the US databases. Second, it allows you to search by IPC and/or ECLA which is the future. The USPC will be gone in nine months and you might as well start boning up on the new system and rewiring your mental pathways.

    BTW, your privacy concerns are very real. Even the trial period searching performed with a private search engine is owned by the service provider. While piecing together a mechanical invention from a few key word strings might be difficult, the folks plugging potentially novel chemical structures into a non-secure engine might be in real trouble.

    That said, handing a confidential disclosure to a third party search firm probably is an even bigger security issue…

  • [Avatar for American Cowboy]
    American Cowboy
    March 19, 2012 10:17 am

    I have that ethical concern, too.
    Google claims that it does no evil, but it tracks your search terms under their new so-called privacy policy.

  • [Avatar for patent leather]
    patent leather
    March 17, 2012 08:54 pm

    Gene, I do some searching myself for clients but I mostly use the USPTO database. I like some private search engines such as Free Patents Online too, but do you think there is any ethical violation about using these private databases for searches on behalf of clients? Of course using the USPTO database is OK, but using a private site gives up your search keywords to a private party who perhaps would be able to determine what the invention you are searching is. I would think reputable sites like FPO or GPS do not review or save search queries, but I tried reviewing both sites once and couldn’t find any statement or guarantee that search queries are completely private and are not saved. So I am reluctant to use such private tools for a search involving any confidential matter due to ethical obligations. Maybe I am just being overly paranoid, but I’d like to hear other patent attorneys’ views on the issue. But if I could get over the ethical issue, I do prefer FPO over the USPTO site because it is faster and provides instant PDFs.