Decode a boat HIN
The example ABC34567H920 is from the Coast Guard’s HIN guide; ABC is the Coast Guard’s own code. Type your boat’s HIN instead.
| Characters | Meaning |
|---|---|
| ABC | Manufacturer identification code (MIC) |
| 34567 | Serial number |
| H | Month of production: August |
| 9 | Year of production: 2019 |
| 20 | Model year: 2020 |
The HIN holds only the last digit of the production year, so the decoder takes the year ending in that digit that is nearest the model year.
Who is ABC? Type the code into “Company Name or MIC” in the Coast Guard’s MIC search.
Decoded in your browser: the HIN isn’t sent or stored, and the link above doesn’t carry it. The decoder reads only the format; it doesn’t look up registration, title or ownership records.
A boat’s hull identification number (HIN) has 12 characters: a 3-character manufacturer identification code (MIC), a 5-character serial number and 4 characters for the dates. In the current format, used since August 1, 1984, character 9 is the month of production (A for January), character 10 the last digit of the year of production and characters 11 and 12 the model year. Boaters often call it a boat VIN, since it does for a boat what a vehicle identification number does for a car. Type a HIN in the decoder above to read it; the HIN stays in your browser.
ABC 34567 H9 20, the Coast Guard’s own example: manufacturer code ABC, serial number 34567, produced in August 2019 (H9), model year 2020.
How to Read a HIN
Each part of the Coast Guard’s example HIN, ABC34567H920:
| Characters | What they are | Example |
|---|---|---|
| 1 to 3 | Manufacturer identification code (MIC), assigned by the Coast Guard | ABC |
| 4 to 8 | Serial number set by the manufacturer: letters and numbers except I, O and Q | 34567 |
| 9 | Month of production, A for January to L for December | H = August |
| 10 | Last digit of the year of production | 9 = 2019 |
| 11 and 12 | Model year | 20 = 2020 |
By the regulation (33 CFR 181.25), characters 9 and 10 give the month and year the boat was certified to meet Coast Guard safety standards, or the date it was built when no certification is required; the Coast Guard’s HIN guide calls it the date of production. Because the HIN holds only the last digit of that year, the decoder takes the year ending in that digit nearest the model year. The model year can run ahead of the production date: the guide’s example BMA45678H485 was produced in August 1984 as a 1985 model. The HIN itself has no spaces or hyphens.
HIN Formats Before August 1984
HINs have been required since November 1, 1972. Until July 31, 1984, builders used one of two older formats; the current format was optional from January 1, 1984 and required from August 1, 1984. All three start with the MIC and the serial number and differ in the last four characters:
| Format | Example | Last four characters |
|---|---|---|
| Straight year, 1972 to 1984 | ABC 12345 08 83 | Month and year of production as numbers: August 1983 |
| Model year, 1972 to 1984 | XYZ 45678 M 84 A | M for this format, model year 1984, month of production with A for August |
| Current, since 1984 | BMA 45678 H4 85 | Month letter with A for January, last digit of the production year, model year 1985 |
Month Letters in a HIN
The two formats that use a month letter count from different months: the current format starts at January, the old model year format at August.
| Letter | Current format | Model year format |
|---|---|---|
| A | January | August |
| B | February | September |
| C | March | October |
| D | April | November |
| E | May | December |
| F | June | January |
| G | July | February |
| H | August | March |
| I | September | April |
| J | October | May |
| K | November | June |
| L | December | July |
State-Assigned and Coast Guard HINs
A person who builds or imports a boat for their own use gets its HIN from the state where the boat is mainly operated (33 CFR 181.23), and states also assign HINs to boats whose original HIN is missing or invalid. A state-assigned HIN starts with the state’s two-letter code and Z, such as FLZ for Florida or CFZ for California, then five serial characters, the month letter and the year it was issued, written as the year’s last digit and its last two digits: TXZ34567A020 was issued in Texas in January 2020. These codes are not always the postal abbreviation (MIZ is Mississippi), so the decoder uses the 56 state and territory codes in the Coast Guard’s downloadable MIC list, dated October 18, 2019. HQZ and USZ mark the rare HINs issued by the Coast Guard and by its National Vessel Documentation Center; the Coast Guard’s HIN guide does not describe their last four characters, so the decoder shows them without a date.
Where to Find the HIN on a Boat
- Boats with a transom: on the starboard (right) outboard side of the transom, within 2 inches of the top of the transom, gunwale or hull-to-deck joint, whichever is lowest.
- Boats without a transom: on the starboard outboard side of the hull, within 1 foot of the stern and 2 inches of the top of the hull side.
- Catamarans and pontoon boats with readily replaceable hulls: on the aft crossbeam, within 1 foot of the starboard hull.
- The duplicate: a second, identical HIN in a place you can’t see from outside, inside the boat or under a fitting. The Coast Guard’s guide notes it has been required since the 1984 update.
The characters are at least a quarter inch high and carved, molded, stamped or otherwise fixed so that changes would show. The letters US- may stand in front of the HIN as the country of origin code, and anything else printed within 2 inches of it must be set apart by a border or a separate label. Removing or altering a HIN is not allowed without the Coast Guard’s authorization (33 CFR 181.35).
Look Up the Manufacturer Code
The Coast Guard keeps the list of manufacturer identification codes, and states use it to confirm the code when they check a HIN. Search it by company name or code in the Coast Guard’s MIC search; each record names the company the code is assigned to, with its address. Keep three things in mind from the Coast Guard’s HIN guide: most codes are three letters, but a few issued until the mid-1990s include a number, such as 4WN; a code can be reassigned once its manufacturer has been out of business for 10 years or more; and for boats built abroad the U.S. importer obtains the code (33 CFR 181.31), as foreign countries use different codes from the U.S. list.
What a HIN Doesn’t Tell You
The HIN holds the manufacturer code, the serial number and the dates, nothing more: no model name, length or engine. This decoder reads that format in your browser and doesn’t look up registration, title or ownership records. The Coast Guard calls the HIN the main way to identify boats subject to recalls, and states use it for registration and titling. One wrong character changes the boat’s identity, so the Coast Guard asks states to watch for lookalikes such as 1 and I or L, B and 8, and 0 and C, D or O; the decoder flags I, O and Q in the serial number, where they are not allowed.
Buying a Used Boat
Before a state issues or renews a registration, or updates its owner, for a boat built or imported since November 1, 1972, it must check that the boat has a primary HIN that meets the federal rules (33 CFR 174.16), so compare the HIN on the transom with the one on the registration. The model year matters for financing too, because older boats get shorter loan terms: see How Long Can You Finance a Boat? While you are at the transom, read the capacity plate as well; the Boat Capacity Calculator explains it. Once the boat is yours, add the HIN to your float plan.
Frequently Asked Questions
How do I read a boat HIN?
A HIN has 12 characters: the 3-character manufacturer identification code, a 5-character serial number, the month of production as a letter (A for January), the last digit of the production year and the 2-digit model year. HINs from before August 1984 may use the straight year or the model year format instead.
Where is the HIN on a boat?
On the starboard (right) side of the transom, within 2 inches of the top. Boats without a transom have it on the starboard side near the stern, and pontoon boats with replaceable hulls on the aft crossbeam. A duplicate HIN is hidden inside the boat.
How do I find the year of my boat from the HIN?
In the current format the last two characters are the model year, and characters 9 and 10 are the month and the last digit of the year of production: ABC34567H920 is a 2020 model produced in August 2019.
Can I find the manufacturer from the HIN?
Yes, from the first three characters, the manufacturer identification code. Search that code in the Coast Guard’s Manufacturer Identification Code list, which shows the company it is assigned to. This page links to that search but never sends it your HIN.
What were the HIN formats before 1984?
From November 1, 1972 to July 31, 1984, builders used the straight year format, which ends in the month and year of production as four numbers (0883 for August 1983), or the model year format, which ends in M, the model year and a month letter where A is August (M84A).
Does the HIN show a boat’s history or owner?
No. A HIN holds only the manufacturer code, the serial number and the dates. This decoder reads that format in your browser and doesn’t search registration, title or ownership records.
Sources
- 33 CFR part 181, subpart C, Identification of Boats (eCFR, current to Oct 19, 2026; read Oct 21, 2026): the 12-character format, the month letters, where the HIN goes and the US- country code. 33 CFR 174.16: the HIN check before a state registers a boat.
- U.S. Coast Guard and NASBLA, Hull Identification Number (HIN) Validation & Verification Guidelines (updated Sep 24, 2020), on the Coast Guard’s HIN guidance page (read Oct 21, 2026): the formats before August 1984, state-assigned and Coast Guard HINs, and the example HINs.
- U.S. Coast Guard, Manufacturer’s Identification Code search and its downloadable list of all codes, dated Oct 18, 2019 (read Oct 21, 2026): the state and territory codes the decoder knows.