Free tools · Patent expiration calculator
When does this patent expire?
A US utility patent filed on or after 8 June 1995 expires 20 years from the earliest US non-provisional filing it claims the benefit of, extended day for day by any patent term adjustment, and cut short if a terminal disclaimer ties it to an earlier patent or a maintenance fee goes unpaid. Enter a patent number below for the date and the record behind it.
By patent number
One number, any format. Pick what you want to know about it, or ask for everything.
Free. Five lookups a day per visitor; fifteen with an email. The examiner's search log is read by a paid transcription, so it is limited to three new patents a day per visitor and twenty for everyone. A patent already read is always free and never counts. Resets at midnight UTC.
Every answer shown here, by email, with a link back. Also lifts your limit to fifteen lookups a day.
Deadline calculators
Dates in, dates out. The IPR one-year bar, the PTAB milestones, a contest's close in your own zone, the PCT national phase and the EP opposition window.
Date the complaint was served (35 U.S.C. §315(b)).
Date the IPR petition was filed.
The close as posted, Eastern Time.
Earliest priority date. 30 months for most offices; 31 for the EP and some others.
Date the mention of the EP grant was published. An opposition is due 9 months later (Art. 99 EPC).
Statutory and rule-based intervals, counted in calendar days; the PTAB lines are the usual milestones, and the Board's own scheduling order governs. Not legal advice. Feeds the invalidity search.
WO / PCT report reader
A WO number in; out: the international search report's citations with their X, Y and A categories and the claims each was aimed at, the earliest priority, the national-phase dates, and whether the US national phase has been entered.
International search report · EPO record
- X
- Y
- A
X: relevant alone. Y: relevant combined with another. A: background. Only the searching authority's own citations are listed, not the applicant's. National-phase limits vary by office; check the WIPO PCT time-limits table for the one you need.
Wayback date-prover
A URL in; out: the earliest archived capture of the page and its link, as a citable line for dating a manual, a datasheet or a product page. A capture proves the page existed by that date; it says nothing about when it was first published. Feeds the non-patent literature sweep.
From the Wayback Machine
About this tool
The tool reads the filing chain, the patent term adjustment printed on the patent, whether a terminal disclaimer was filed, and the maintenance-fee events. Fees fall due at 3½, 7½ and 11½ years from grant, with a six-month grace period; a patent whose fee was not paid lapses at the end of that window.
Foreign priority and provisional applications do not count toward the 20 years. Design patents granted from applications filed on or after 13 May 2015 run 15 years from grant instead.
For an invalidity search the expiry date bounds the damages window: a patent that has expired can still be asserted for past infringement, up to six years back from the complaint.
Questions
- Does patent term adjustment always extend the term?
- Only where the Patent Office caused delay beyond its statutory deadlines, reduced by any delay the applicant caused. The adjustment is printed on the face of the patent; the tool reads it from there.
- What does a terminal disclaimer do to expiry?
- It makes the patent expire no later than the earlier patent it was disclaimed over. The tool flags a terminal disclaimer when the record shows one; the date of the earlier patent then governs.
- How long does a patent filed before June 1995 last?
- The longer of 17 years from grant or 20 years from filing, for patents that were in force on 8 June 1995 or issued from applications filed before that date.