Guide · Patent term
“20 years” is the start of the answer, not the end.
A US utility patentutility patentThe most common type of patent — covers functional inventions. 20-year term from filing.Read more → runs 20 years from its filing datefiling dateThe day the patent application was submitted to the USPTO. Sets the priority date for prior-art comparisons.Read more → — but that clock gets adjusted. The patent office's own delays add time back, regulatory review can extend it, and a terminal disclaimerterminal disclaimerA filing that ties one patent's expiration to an earlier related patent's. Often required to overcome obviousness-type double-patenting rejections.Read more → can cut it short. Here's how a patent's real lifespan is actually set.
The baseline
20 years from filing — not from grant.
Since 1995, a US utility patentutility patentThe most common type of patent — covers functional inventions. 20-year term from filing.Read more → expires 20 years after its earliest non-provisionalprovisionalA simplified, lower-cost patent application that locks in a filing date for 12 months while the inventor refines or pitches.Read more → filing datefiling dateThe day the patent application was submitted to the USPTO. Sets the priority date for prior-art comparisons.Read more →. That's a crucial distinction: the clock starts when you file, not when the patent issues — so years spent in examination eat into your protection. (A design patentdesign patentCovers the ornamental appearance of a product, not function. 15-year term from grant.Read more → is different: 15 years from the grant dategrant dateThe day the USPTO officially granted the patent. Enforceability typically starts here.Read more →, with no maintenance feesmaintenance feesPeriodic fees the USPTO charges to keep a granted utility patent in force (3.5, 7.5, 11.5 years post-grant). Miss one and the patent expires early.Read more →.)
And the term only holds if you keep paying: US utility maintenance fees fall due at 3.5, 7.5, and 11.5 years after grant. Miss one and the patent lapses early, no matter what the 20-year date says.
What moves the expiry date
When the USPTO is too slow, you get the days back. If the office misses its own deadlines (like 14 months to a first action) or takes more than 3 years to grant, those days are added to the term — minus any delay you caused. Printed right on the granted patent.
For products that need regulatory approval — drugs, biologics, some devices — you can restore time lost waiting on the FDA. Up to 5 years, capped so no more than 14 years remain after approval, and only one patent per product. This is the lifeblood of pharma patents.
To overcome an obviousnessobviousnessA 103 rejection: the invention would have been obvious to a skilled person who combined existing prior art. The most common rejection in patent prosecution.Read more →-type double-patenting rejection over your own related patent, you disclaim the term that would extend past that earlier patent. It ties the two expiries together and requires common ownership — deliberately giving up term.
Putting it together
The real expiry, in one line.
expiry = filing date + 20 years + PTA + PTE − terminal disclaimer
For most patents PTA and PTE are zero and the answer really is 20 years from filing. But for a patent that sat years in a slow examination, or a drug that waited on the FDA, the adjustments can shift the date by years — which is exactly why an acquirer or litigator always recalculates the true term rather than trusting the filing datefiling dateThe day the patent application was submitted to the USPTO. Sets the priority date for prior-art comparisons.Read more → alone.
Calculate it
Find a patent's expiry and fee schedule.
Our expiry tools compute the 20-year date and the maintenance-fee deadlines, and you can export them to your calendar.
A plain-English overview, not legal advice. PTA and PTE calculations are technical and fact-specific — confirm a critical date with a patent attorney. PatentBrief is not a law firm.