Patent Number, Publication Number

A patent number, or sometimes referred to as a publication number, is a number identifier that is assigned to a patent application when it is published by the issuing patent office. 

The number can be seen on the patent document under INID code 11. The format of this number identifier may vary depending on the issuing office and the type of patent application. However, the most general outline of all patent numbers contains a combination of some or all of the following sections (see also the image below). This general format can change during the life time of the patent for different reasons. 

  • A two-letter code identifier for the country where the patent is filed.Also referred to as the country code
  • A special (type/class code) 1-2 digit or letter code which is typically used to indicate the type of the patent i.e. patent, utility model, design etc. (this code is determined by the relevant patent office and is only used by some offices). 
  • The year identifier (typically 2 or 4 digits) referring to the year the patent was issued. (This is not used by all offices or during the whole application process) 
  • A unique serial number containing several digits (typically 5-8 digits). (This could be a continuous series or an annual series if the year identifier is used) 
  • A kind code, which indicates the type of publication, and status of the patent (typically 1 letter appended by 1 optional digit). 

Patent offices may change (have changed) the format of its patent numbering system over the years. Therefore, one may see a different patent number format from the same patent office depending on the time period when the patent was issued. Also note that some patent offices may use a different format after the patent is granted as compared to when the patent application is under examination (e.g. the US patent office), while others (e.g. EPO or China) keep the same number series but use the kind code to distinguish them. 

A patent number indicates that a product or invention is protected by a patent application, which means that the patent owner has all the rights to this invention and can stop others from using it without a license. It is therefore usual to find patent numbers inscribed on a commercial product or in the product documentation to indicate ownership of the rights and to prevent others from unlawfully copying the solution.  

The following table shows the currently used patent number formats from selected patent offices. For earlier number systems please consult the relevant patent office. 


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