How Long Does a US Patent Last?

The standard answer is 20 years, but that is just the baseline. The actual expiration date depends on a few things that can push it earlier or later.

The 20-Year Rule

A US utility patent expires 20 years from its earliest effective filing date, which is the date the application was filed with the USPTO.

This applies to utility patents filed on or after June 8, 1995. Before that date, patents lasted 17 years from the grant date or 20 years from filing, whichever was longer.

Design patents work differently: 15 years from the grant date, or 14 years if filed before May 13, 2015.

What Can Add Time

Patent Term Adjustment (PTA)

When the USPTO takes longer than allowed to process a patent application, the patent owner gets extra days added to the end of the term. This is called Patent Term Adjustment and applies to patents filed on or after May 29, 2000.

PTA ranges from zero to several years depending on how long examination took. It is printed on the face of the patent and available in USPTO records.

Patent Term Extension Under Section 156

Certain pharmaceutical and medical device patents can qualify for an extension under 35 USC 156 if the product went through a lengthy FDA regulatory review. The extension compensates for time the patent could not be used commercially. The maximum is 5 years, and the total post-approval term cannot exceed 14 years.

What Can End a Patent Early

Unpaid Maintenance Fees

Utility patents require three maintenance fee payments after grant, at 3.5, 7.5, and 11.5 years. Miss a payment and the patent lapses on that anniversary date, before reaching the 20-year mark.

Terminal Disclaimers

When related patents are filed on similar inventions, the USPTO may require a terminal disclaimer, a filing that ties the newer patent's expiration to an earlier one in the family. The newer patent cannot outlive the one it was disclaimed against.

Continuity Applications

When a patent claims benefit from an earlier parent application (a continuation or divisional), the 20-year clock runs from the earliest effective filing date in the chain, not from when the continuation was filed.

A continuation granted today but tracing back to a parent filed 15 years ago has roughly 5 years of remaining term, not 20.

How the Expiration Date Is Calculated

The USPTO does not print an expiration date on patents. Getting to the real number requires checking the filing date, any continuity chain, PTA from the grant record, the maintenance fee payment history, any Section 156 extension, and any terminal disclaimers.

Patent Sunset is a free calculator that looks up and calculates expiration dates for US patents using USPTO data.