If you are managing an international patent filing, deadlines are everything. This PCT deadline calculator helps you quickly estimate the most common Patent Cooperation Treaty time limits from your earliest priority date so you can plan filings, budget foreign prosecution, and avoid expensive surprises.
PCT Deadline Calculator
Enter your case dates below and click Calculate. This tool estimates core deadlines such as 12-month priority, Article 19 timing, Chapter II demand timing, and national phase entry dates (30/31/32 months).
What this PCT calculator covers
This calculator focuses on practical dates used in most PCT docketing workflows. Specifically, it computes:
- 12-month Paris priority deadline (common target for filing a PCT application).
- 14-month restoration window marker (important in some late-priority scenarios).
- 16-month date from priority (used in Article 19 timing analysis).
- 18-month publication marker (international publication timing reference).
- Chapter II demand deadline estimate: later of 22 months from priority or 3 months from ISR transmittal date (if provided).
- National phase entry dates at 30, 31, and 32 months from priority.
How to use it in practice
1) Enter the earliest priority date
This is usually your first-filed application date (for example, a US provisional or national filing date you are claiming).
2) Add ISR/Written Opinion date if available
When this is entered, the calculator can apply the “later-of” logic for Article 19 and Chapter II demand estimates more realistically.
3) Review and verify jurisdiction-specific rules
Different designated/elected Offices may have local requirements, translations, fees, and exceptions. Always confirm with current WIPO resources and local counsel before acting.
Key PCT time limits explained
12 months from priority
In many cases, this is the critical deadline to file the PCT application while preserving the priority claim under the Paris Convention framework.
18 months from priority
PCT applications are generally published around 18 months from the earliest priority date, giving the public visibility into the invention.
Article 19 amendment timing
The practical rule is often calculated as the later of 16 months from priority or 2 months from ISR transmittal. This calculator applies that logic when you provide the ISR date.
Chapter II demand timing
A common planning rule uses the later of 22 months from priority or 3 months from ISR transmittal. If no ISR date is entered, the calculator shows the 22-month marker only.
30/31/32 months national phase entry
Many countries use a 30-month national phase deadline; others use 31 months, and a few allow different time limits. This is why docketing teams often track multiple national phase dates simultaneously.
Common mistakes to avoid
- Using the international filing date instead of the earliest priority date as the baseline for national phase calculations.
- Ignoring local formalities such as translations, powers of attorney, inventor declarations, and fee timing.
- Assuming all countries use exactly the same national phase deadline.
- Failing to account for time zone and office closure rules on the filing day.
Important disclaimer
This calculator is for educational and planning purposes only and is not legal advice. PCT time limits can vary by fact pattern, office practice, and legal updates. Always verify deadlines with official sources (including WIPO guidance) and qualified patent counsel before filing.