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How to read a patent number

A published patent number usually combines a country or office code, a serial number and a kind code that says what type of document it is.

• Records on this site write US patents as the office code and the number with commas, for example US 2,292,387. Google Patents shows the same patent as US2292387A, with the letter A as the kind code.²
• On US documents published before 2 January 2001, the kind code A meant a granted patent. From that date, B1 marks a patent with no earlier pre-grant publication and B2 a patent that was published earlier as an application.¹
• Since 2001 the USPTO has also published patent applications before grant, with the kind code A1. A publication is not a granted patent.¹
• Other USPTO kind codes include E for a reissue patent, S for a design patent and P2 or P3 for a plant patent.¹
• European patents use the prefix EP, for example EP 0789867 B1.³

Sources

1. United States Patent and Trademark Office, Kind Codes Included on the USPTO Patent Documents (accessed 2026-10-27)
2. Google Patents, US2292387A Secret communication system (accessed 2026-10-27)
3. Google Patents, EP0789867B1 (accessed 2026-10-27)