Enter the 7 digits of the EP publication number (e.g. 1111111)


Calculate if it is possible to file an opposition against a European patent, which EPO office fee must be paid, and how much time is left to file the patent opposition. The EPO Opposition Calculator is based on real-time data from the European Patent Office (EPO).

How does the EPO Opposition Calculator work?

All you need is the publication number of a European patent application or a European patent, in the format EP1234567…. Only the seven digits are important. Neither “EP” nor the code following the seven digits (A1, A2, A4, B1, B2, …) matter for the calculator. The EPO Opposition Calculator looks at all available documents and uses the most relevant one for the calculation.

Where can I find this publication number?

Publications of European patent documents can be viewed free of charge at various places. For example, at these links:

Does the EPO Opposition Calculator accept both patents and patent applications?

Yes. The EPO publishes a patent document in different versions (application, patent, amended patent, etc.), but always with the same seven digits. If the EPO Opposition Calculator determines that the search query is for a European patent application, this result will be output accordingly.

Does the EPO opposition calculator also calculate oppositions against German patents?

The present calculator only calculates oppositions against European patents. Oppositions against German patents cannot be calculated with the EPO Opposition Calculator.

What exactly does the EPO Opposition Calculator calculate?

For each valid search query, the EPO Opposition Calculator calculates the following aspects:

  1. Whether there is a granted EP patent (yes/no)
  2. (if yes) whether an opposition can be filed against the EP patent
  3. (if yes) when the deadline for filing the opposition expires
  4. (if yes) what opposition fee (official fee) is to be paid
  5. (if no) alternative courses of action to attack the searched EP patent document

What information does the EPO Opposition Calculator provide?

The following key statements are made:

  1. Opposition possible: (yes/no)
  2. Reason: brief explanation
  3. Proposal for action: short statement on further action, for example remaining days
  4. Comment: brief statement on deadline, for example, whether deadline fell on weekend or closing day.
  5. Opposition fee: indication of the objection fee

In order to enable the user to critically check the determined data, the EPO Opposition Calculator provides the following additional information:

  1. Publication number: EP…….A1/B1 etc. The seven digits correspond to your input. The following code (A1, B1, etc) indicates on which document the analysis was based.
  2. Application number: the application number associated with the publication number. This can be looked up on the publication itself.
  3. Title: the title of the document searched.
  4. Applicant(s): the applicant(s) of the document searched.
  5. Inventor: the inventor(s) of the searched document
  6. Earliest priority date: the earliest priority date of the searched document
  7. Filing date: the filing date of the searched document
  8. Publication date: the date of publication of the document mentioned in point 1. Important: this is not always the date of publication of the application or patent, but the date of publication of the version (A1, B1, etc., as mentioned in point 1).

Furthermore, a link for contacting is provided.

Does the EPO Opposition Calculator take into account weekends and EPO closing days?

The possibility to file an opposition against a European patent is strictly limited to 9 months from the publication of the grant decision. If the end of these 9 months falls on a weekend or a day on which one of the EPO offices is closed, this period is extended accordingly to the next working day.

In addition to weekends and holidays, the EPO is also closed on self-selected bridge days. All such closing days are published annually by the EPO for the following year. EPO Closing Days for 2023.

For 2023, the EPO Opposition Calculator includes both weekends and EPO closing days. For 2024, only weekends are currently considered.

Can I mandate you with filing an opposition right away?

Prior to any engagement, we must ensure that there are no conflicts of interest. Furthermore, we must verify that we have sufficient capacity available to fulfill your request in a timely manner. If you are interested in an opposition or other action, please click on the contact box shown. We will get back to you within a short time.

Errors in the EPO Opposition Calculator

Errors may occur. In this case, please click on the contact form and submit this. We will repeat the search query and try to fix the error.

The search does not work

This may be due to several reasons:

  1. EPO data service is offline: This often occurs at 03:00 UTC, usually daily. Please try again in a few minutes.
  2. Data does not exist: there is currently or generally no data set for your search query
  3. Data corrupted: our search is based on JSON and XML files from the EPO. Errors may occur when creating these files (EPO) and when reading them.
  4. Rate limiting. The use of the EPO Opposition Calculator is limited in time and scope. Please try again in a few hours.

Will my searches be stored?

Every search is anonymous. Under no circumstances will your personal data, such as IP address, country, etc, be linked to, stored in, or analyzed in connection with a search performed. Naturally, anonymous data on individual searches may remain temporarily stored in our system as well as in the EPO’s system. Temporary data on searches are routinely deleted from our systems without being viewed by us or third parties.

Is it possible to use the EPO Opposition Calculator on my website?

It is possible. Please contact us using the contact details above.

When was the EPO Opposition Calculator last updated?

The EPO Opposition Calculator was last updated in June 2023.

Why does the EPO opposition calculator not yet recognize document XY?

The EPO Opposition Calculator obtains data from a data service of the European Patent Office and is subject to their update cycles. Please let us know exactly which document it is and we will try to get to the bottom of it.

Mobile hero image Dr. Michael Plevan

German Patent Attorney

European Patent Attorney

UPC Representative

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