A patent’s term is the period of time during which the granted rights are enforceable by the holder of the patent. How long does a patent last? Today’s two-minute drill addresses how terms are calculated for some different types of patents issued in the United States.

I’ll start with the easy one. For a design patent issued off an application filed on or after May 13, 2015, its enforceable term begins on its grant date and generally ends 15 years from the grant date.35 U.S.C. § 173.

Utility patent terms are slightly more complex, because their terms can depend upon a variety of factors related to the patenting process. Similar to a design patent, the enforceable term of a utility patent begins on its grant date.35 U.S.C. § 154. However, the date the term concludes is not calculated based on the patent’s grant date. Rather, it is generally 20 years from the first non-provisional application’s filing date.See id. (For example, where a patent is granted off of a first continuation application, the first non-provisional application would be the parent application.). Thus, a longer patent prosecution process can result in a shorter enforceable term.

There is some nuance in a utility patent’s term calculation. Inter alia, if priority to a U.S. provisional patent application was claimed, the priority claim isn’t taken into account when calculating the patent’s term.See Id. at § 154(c)(3). Thus, a patent’s term could end 21 years from the filing date of a provisional patent application.

Maintenance fees must further be paid at intervals after the grant of a utility patent.35 U.S.C. § 41(b) Failure to pay can result in an unenforceable expired patent.Id. at § 41(b)(2). Design patents do not require maintenance fees to be paid.Id at § 41(b)(3).

There are additional adjustments (e.g., patent term adjustments and terminal disclaimers) that could apply to a patent’s term, so it’s always best to consult with a patent attorney to determine whether a patent is active or for how long it will be enforceable.