Free tools · Pre-cutoff census
How big is the field a prior-art search has to cover?
Enter a US patent number below and the tool counts the granted US patents dated before its prior-art cutoff in each CPC subclass the patent itself is classified in. The counts show how large each part of the field is, and where a search will have to narrow.
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
A subclass with a few hundred earlier patents can be read in full; one with tens of thousands needs a narrower approach. The census tells you which you have before any searching starts.
Counts are granted US patents only, so they exclude published applications, foreign art and literature, which add to every field.
Questions
- What is a CPC subclass?
- The Cooperative Patent Classification, shared by the USPTO and EPO, sorts patents by technology. A subclass is the four-character level such as H04L or A61B, each divided into many groups.
- Why count before the cutoff only?
- Only art that predates the cutoff can invalidate the patent, so that is the field a search has to cover.