Free tools · Prior-art cutoff date
What is this patent's priority date, and what must prior art predate?
Prior art must predate the patent's effective filing date: the priority date of the earliest application that supports the claim, or the actual filing date if no earlier application does. For patents with an effective filing date on or after 16 March 2013 the AIA first-inventor-to-file rules apply; earlier patents fall under the pre-AIA rules. Enter a patent number below and the tool prints both dates and which rules govern.
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 patent's own record and reports the earliest priority claim, the US filing date, and the AIA or pre-AIA status that follows from them. It does not choose between the two dates for you, because the choice depends on the claim: a claim is entitled to the priority date only if the earlier application describes and enables what that claim recites.
If a reference falls between the two dates, whether it is prior art turns on that support question — the first thing to settle before anyone searches.
Questions
- Is the cutoff the priority date or the filing date?
- The priority date, if the earlier application supports the claim being challenged; otherwise the filing date. The tool shows both and the gap between them.
- Does a provisional application set the cutoff?
- It can. A provisional application counts as a priority date for any claim it fully supports. It does not start the 20-year patent term.