Trademark serial number format checker.

A trademark filing carries two different numbers that people constantly swap: the serial number USPTO gives an application the day it is filed, and the registration number it receives only if the mark makes it onto the register. They have different lengths, they are searched separately, and a mark that was refused or abandoned has a serial number and no registration number at all. This checker classifies a number by its length and decodes the series code in a serial number.

How this is calculated

USPTO's data documentation describes the serial number as an eight-position numeric field whose first two digits are a series code, followed by a six-digit number padded with zeros, and the registration number as a seven-position numeric field right-justified with leading zeros. USPTO's July 2026 notice confirms that every application gets an eight-digit identifier. The page therefore calls an eight-digit entry a serial number and an entry of seven digits or fewer a registration number (padded to seven), and reports anything longer as neither.

The series codes in that documentation are 70 (filed 1881 to March 31, 1905), 71 (to December 31, 1955), 72 (to August 31, 1973), 73 (to November 15, 1989), 74 (to September 30, 1995), 75 (to March 19, 2000), 76 (March 20, 2000 onward, paper filings) and 78 (March 20, 2000 onward, electronic TEAS filings). When a serial number begins with 80, 81 or 82 the real serial number is unknown and USPTO builds one by putting an 8 in front of the seven-digit registration number, so the page shows the registration number hidden inside it. A 89 prefix marks non-registration data entered for treaty or statutory reasons. The July 2026 notice adds that applications had reached the 99 series, that a new series starting with 50 begins July 18, 2026, and that Madrid Protocol extensions keep the 79 prefix. Other prefixes are not described in the documents opened for this page, and the checker says so rather than guess. Sources read 2026-10-26.

Worked example

78123456 has eight digits, so it is a serial number. Its series code is 78, which USPTO's documentation assigns to electronically filed applications from March 20, 2000 onward. 80123456 also has eight digits but starts with 80, so the registration number inside it is 0123456. 123456 has six digits, so it reads as a registration number and is written 0123456 in seven positions. 79123456 starts with 79, the Madrid Protocol series. These numbers are illustrations, not real filings.

Mistakes people make

• Searching a registration number as a serial number. A seven-digit entry is a registration number. Choose the matching search type in TSDR.
• Using the series code to date a filing. USPTO says to use the filing date and time for priority, not the number.
• Assuming every serial number starts 7x. New applications now start with 99 and, from July 18, 2026, 50.
• Looking for a registration number on a pending mark. A pending application has none yet.

Who this is for, and what it does not cover

It suits business owners, paralegals and anyone with a number on a filing receipt or an Office action who is not sure which kind it is. It does not confirm that a number exists, return a mark's status or owner, or recognise international registration numbers issued by WIPO. For status, open USPTO's TSDR and enter the number there.

Sources

Retrieved 2026-10-26. Each source was opened and read against the claim next to it.

• USPTO Trademark Applications Daily XML documentation (V2.0): the serial-number element (eight positions, series code in positions 1-2, series code table, the 80/81/82 and 89 notes) and the registration-number element (seven positions, leading zeros).
• USPTO Trademark Alert: New serial number series begins for applications (published 07/01/2026): eight-digit serial numbers, the new series starting with 50 from July 18, 2026, the 99 series, and that Madrid extensions still begin with 79.
• USPTO Trademark Status and Document Retrieval (TSDR): where status is looked up by serial or registration number.
• USPTO Trademark Search: USPTO's search system for the register.