In US patent law, a utility patent generally lasts 20 years from the application’s filing date.
The modern 20-year term was established by the Uruguay Round Agreements Act of 1994, which changed the system for applications filed on or after June 8, 1995. Before that change, utility patents generally lasted 17 years from the date they were granted. The newer approach ties the term to filing, rather than examination and issuance time.
The calculation can use the earliest filing date of a qualifying related nonprovisional application. A provisional application does not itself become a patent, but its 12-month period generally is not counted against the eventual 20-year term. Patent term adjustment or extension may also add time in certain circumstances, such as qualifying administrative delays or approval-related delays.
A common mix-up is the 14-year term historically associated with design patents, not utility patents. Today, qualifying design patents generally last 15 years from grant, while utility patents also require periodic maintenance fees to remain in force.