Patent term calculator

The United States Patent and Trademark Office does not calculate expiration dates for patents. In response to patent owner and public inquiry, the USPTO is providing a downloadable patent term calculator as a resource to help the public estimate the expiration date of a patent. The calculator can be used to estimate the expiration dates of utility, plant, or design patents. The calculator contains prompts to enter specific information related to the patent in order to help in estimating expiration dates. This information can be obtained from USPTO's online systems, links to which are provided below.


Download Patent Term Calculator

Download the calculator by right-clicking the link below and selecting the option to save the file to your computer.  Creating additional local copies or renaming the files will not alter the calculations.  Please enable macros in order to use all features of the calculator.  Do not try to use the file by simply clicking on it and opening it using a viewer embedded in your web browser - the calculator will not work properly unless the file has been saved locally and opened in MS Excel software.

>> Right Click to Download Patent Term Calculator [MS Excel] (last update April 4, 2018) 
       Includes technical updates to eliminate a macro overlap problem for some power users of Microsoft Excel and clarifies some instructions.   The calculations are unaltered from the prior version.


This calculator is only an educational tool. It was developed based on assumptions that may or may not apply in a particular case. It does not provide a determination of any kind by USPTO. It is not intended to, and does not, create any right or benefit, substantive or procedural, enforceable at law or in equity by a party against the United States, its departments, agencies, instrumentalities, entities, officers, employees or agents, or any other person.

Other sources of patent term data may exist that are not maintained by the USPTO. One such source is the FDA's Orange Book for Approved Drug Products with Therapeutic Equivalence Evaluations which includes patent expiration dates, some of which may include periods of exclusivity administered by the FDA that add onto patent term. Additional patent term may also be privately granted by an Act of Congress, and court decisions may establish patent expiration dates that are not reflected in USPTO records.


For questions on patent term, USPTO's Office of Patent Legal Administration help line at 571-272-7702 is available as a resource. For advice in a particular case, a registered patent practitioner or attorney should be consulted.

Guide to Locating Information Required for Estimating a Patent Term Expiration Date

The following document is provided to assist you in locating information required for estimating a patent term expiration date:

Factors to Consider for Patent Term Calculations

Since the term of a patent for utility/plant patent(s) is no longer based upon a term fixed at grant, the number of factors that must be considered increase the difficulty in calculating the term of a patent. A patent owner or the public must consider the following factors in calculating the expiration date of a patent for utility and plant applications. The factors include the following:

  • type of application(utility, design, plant);
  • filing date of the application;
  • the grant date of the patent;
  • benefit claims under 35 U.S.C. § 120, 121 or 365(c);
  • patent term adjustments and extensions under 35 U.S.C. § 154;
  • patent term extensions under 35 U.S.C. § 156;
  • terminal disclaimer(s); and
  • timely payment of maintenance fees.

System links to help determine these factors:

Importance of Patent Term Calculations

The term of a patent is important in that it provides the specified period for infringement. In general, for the term of a patent, whoever without authority makes, uses, offers to sell or sells the patented invention, within the United States, or imports into the United States any patented invention during the term is an infringer of the patent and may be subject to monetary damages, injunction and other forms of legal relief.

History of Changes to Patent Terms

The term of the patent has been changed by Congress a number of times since 1790:

  • Initially, under the 1790 Patent Act the term could not exceed 14 years.
  • In 1836, Congress passed the Patent Act (5. Stat 117, 119, 5) which amended the statute to provide a term that could last for 21 years by providing for a 7 year extension from and after the expiration of the first term.
  • In 1861, Congress again changed the term to 17 years with no extension.
  • In 1994 the US signed the Uruguay Round Agreements Act changed the date from which the term was measured. Because the term was measured from the filing date of the application and not the grant date of the patent, Congress amended 35 U.S.C. § 154 to provide for applications filed after June 7, 1995 that the term of a patent begins on the date that the patent issues and ends on the date that is twenty years from the date on which the application was filed in the U.S. or, if, the application contained a specific reference to an earlier filed application or applications under 35 USC 120, 121 or 365(c), twenty years from the filing date of the earliest of such application. In addition, 35 U.S.C. 154 was amended to provide term extension if the original patent was delayed due to secrecy orders, interferences, or appellate review periods.
  • In 1999, Congress amended 35 U.S.C. § 154 to provide for additional patent term if the USPTO failed to meet certain statutory deadlines that guarantee prompt patent and trademark office responses and guarantee no more than a 3 year application pendency. Applications filed after May 28, 2000 became subject to the changes to 35 USC 154(b).
  • On December 18, 2012, the Patent Law Treaties Implementation Act of 2012 (PLTIA) was signed into law. The PLTIA among other things set forth provisions implementing the 1999 Geneva Act of the Hague Agreement Concerning the International Registration of Industrial Designs ("Hague Agreement"). These provisions (Title I of the PLTIA) take effect on May 13, 2015.  Per this agreement,  U.S. design patents resulting from applications filed on or after May 13, 2015 will have a 15 year term from issuance.  Design applications filed before May 13, 2015 will continue to have a 14 year term from issuance.

Calculator Improvement and Feedback

We are interested in hearing from you regarding the ease of use and accuracy of this web page, the Patent Term Calculator and the Quick Guide. So that we may continually refine the language, structure, calculations, and examples to ensure that the explanations meet the needs of all users and the calculations capture all situations, please provide constructive comments regarding this patent term calculator to

We would also be pleased to know if this calculator is meeting your needs. Thank you for taking the time to work with us on improving this educational tool!