United States · Patents · Number formats
US patent number format validator.
Paste a patent number in any common style and get the type, the zero-padded form the USPTO search expects, and roughly when numbers like it were granted.
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Result
Enter a number and press Check.
The formats the USPTO publishes
The USPTO's Patent Number page lists the series and how to type them into its search: a patent number must include at least seven characters, with leading zeros added between any letter prefix and the digits to reach that length. Its examples are below.
| Type | Prefix | USPTO example |
|---|---|---|
| Utility | none | 5778 is entered as 0005778; 12,156,579 as 12156579 |
| Reissue | RE | RE00126 |
| Plant | PP | PP00126 |
| Design | D | D000126 |
| Addition of improvement | AI | AI00126 |
| X patents | X | X000001 |
| H documents | H | H000001 |
| T documents | T | T100001 |
How the tool reads what you type
It removes commas, spaces, dots and the words US, Pat. and No., then looks for an optional prefix (RE, PP, D, AI, X, H or T), the digits, and an optional kind code such as B2 or S. So US 10,123,456 B2, 10123456 and U.S. Pat. No. 10,123,456 all give the same result. The output has four parts: the patent type, the kind code it found, the form to type into USPTO search, and the display form with commas.
Why seven characters
The USPTO says a search entry needs at least seven characters. A utility patent number of 5,778 is therefore typed 0005778, and a design number D126 is typed D000126. Utility numbers at or above 10,000,000 simply have eight digits and need no padding. The tool rejects a utility number of more than eight digits, because no such number has been issued.
Using the number to estimate a date
Utility patents are numbered in sequence, so the number gives an approximate grant date. The USPTO's milestones page dates these numbers:
| Utility patent No. | Granted |
|---|---|
| 1,000,000 | August 8, 1911 |
| 5,000,000 | March 19, 1991 |
| 10,000,000 | June 19, 2018 |
| 11,000,000 | May 11, 2021 |
| 12,000,000 | June 4, 2024 |
The USPTO milestones page also records design patent D1,000,000 on September 26, 2023. The tool uses these anchor points to say that a number falls between two of them. It is an era, not a grant date. For the exact date, search the number on the USPTO's patent search.
Worked example
Enter US 10,123,456 B2. The tool strips the prefix and commas, finds the digits 10123456 and the kind code B2, and reports a utility patent. The search form is 10123456, and the grant era is between No. 10,000,000 (June 19, 2018) and No. 11,000,000 (May 11, 2021). Enter D126 and you get the design patent search form D000126 and a note that design numbers below D1,000,000 predate September 26, 2023. The numbers are examples; the tool does not check that either exists.
Edge cases and common mistakes
- Mixing up patent numbers and application numbers. A patent number is assigned when the patent is granted; an application has its own serial number and a publication number. This tool does not read those.
- Leaving the kind code on. B2 is not part of the number, though it is useful: see the kind code lookup.
- Typing a design number as a plain number. Without the D prefix it is read as a utility patent.
- Forgetting the padding in USPTO search. Without leading zeros a short number may return no result.
Who this is for, and what it does not cover
Researchers, paralegals, founders and inventors who copy patent numbers from different places in different styles. The tool does not confirm that a patent exists, whether it is in force, who owns it, or when it expires. For maintenance fee timing use the US patent maintenance fee due dates page. It covers United States numbers only; it does not read Canadian, European or PCT numbers.
Related identifier pages
Other identifier formats on this site: US EIN validator, ITIN format validator, SSN format validator and the full list of ID validators.
Sources
- USPTO: Patent Number — seven-character minimum, leading zeros, and the RE, PP, D, AI, X, H and T prefixes
- USPTO: Milestones in U.S. patenting — utility patent Nos. 1,000,000 through 12,000,000 and design D1,000,000 with grant dates
- USPTO: patent search — official place to search a number
Every URL above was fetched in October 2026 and every figure on this page is taken from it. Agencies revise formats, so confirm anything that matters against the current official page.
Frequently asked questions
How many digits is a US patent number?
The USPTO says patent numbers have seven or more digits. Utility patents granted since No. 10,000,000 on June 19, 2018 have eight digits.
What do the prefixes RE, PP and D mean?
RE marks a reissue patent, PP a plant patent and D a design patent. A number with no prefix is a utility patent. The USPTO also lists AI, X, H and T series.
Why does the USPTO search want leading zeros?
Its Patent Number page says an entry must include at least seven characters, with zeros added to reach that length. 5778 is entered as 0005778 and RE126 as RE00126.
Is the kind code part of the patent number?
No. A kind code such as B2 follows the number and says what kind of document it is. This tool strips it and reports it separately.
Can I tell when a patent was granted from its number?
Roughly. Utility patents are numbered in sequence, and the USPTO dates No. 10,000,000 to June 19, 2018 and No. 12,000,000 to June 4, 2024, so a number between them was granted in that span.
Is a patent application number a patent number?
No. An application has its own serial number and may have a publication number. A patent number exists only once the patent is granted.
Does a passing result mean the patent exists?
No. It means the value has the shape of a US patent number. Search it on the USPTO site to confirm that it was issued.
Does this tool work for Canadian or European patents?
No. It reads US formats only. Canadian patent expiry has its own calculator on this site.
Format check, not verification
The check confirms only that a value has the shape of a US patent number and gives a rough grant era from USPTO milestones. It does not show that a patent exists, is in force, or belongs to anyone. This is not legal advice.