Like most luxury watches, Audemars Piguet timepieces carry a set of identifying numbers. Among the most important is the serial number, which helps verify authenticity and trace a watch's production history. Whether you're buying, selling, researching, or simply documenting your collection, knowing where to find these numbers — and what they mean — is essential.
Unlike model or reference numbers, which apply to all watches of a specific type, serial numbers are unique to each individual timepiece. Audemars Piguet officially refers to its serial numbers as case numbers. In addition to the case number, Audemars Piguet also uses movement numbers, which are equally important when verifying authenticity, documenting a watch, or requesting an Extract from the Archives.
In this guide, we'll walk through where to find Audemars Piguet serial numbers, how to understand them, and how they can be used when researching or authenticating an AP watch.
Table of Contents
Audemars Piguet Movement Numbers, Explained
Every Audemars Piguet watch contains a movement number engraved on the baseplate or on a bridge of the caliber. This number is unique to the movement and has been recorded in AP's production registers since the early years of the company. Because the earliest register has been lost, documented movement numbers begin in 1882, starting at 2000 and increasing sequentially from there. These registers list the movement number alongside details such as complications, mechanism type, and, in some eras, elements of the exterior.
Movement numbers were assigned sequentially, but the sequence does not reflect total production. In the late 19th and early 20th centuries, Audemars Piguet did not use every number in order; only about half of the numbers in those ranges were allocated. Additionally, movement blanks were typically numbered when AP acquired them, not when they were finished or cased. As a result, some movements sat for years, even decades, before being completed.
Taken together, these factors mean that a movement number can indicate a general era, but not an exact production year.
By 2017, Audemars Piguet approached the upper end of six-digit movement numbering. Rather than issue a movement marked "1,000,000," the brand transitioned to a new alphanumeric format that includes two letters followed by four digits (starting with AA0001 through AA9999, then AB0001, and so on).
Movement Number Lookup Table
Knowing the movement number of an Audemars Piguet watch can help date the general production era of the watch.
| Production Years | Movement Number From | Movement Number To |
|---|---|---|
| 1880-1889 | 2,000 | 4,500 |
| 1890-1899 | 4,000 | 6,500 |
| 1900-1909 | 6,000 | 14,000 |
| 1910-1919 | 11,000 | 27,000 |
| 1920-1929 | 23,000 | 42,000 |
| 1930-1939 | 41,000 | 45,000 |
| 1940-1949 | 44,000 | 60,000 |
| 1950-1959 | 55,000 | 80,000 |
| 1960-1969 | 72,000 | 120,000 |
| 1970-1979 | 110,000 | 230,000 |
| 1980-1989 | 220,000 | 350,000 |
| 1990-1999 | 330,000 | 490,000 |
| 2000-2009 | 475,000 | 750,000 |
| 2010-2017 | 700,000 | 999,999 |
| 2017 onwards | Two letters + four digits (e.g., AA0001) | |
Audemars Piguet Serial Numbers (Case Numbers), Explained
On an Audemars Piguet watch, the serial number is the case number, historically referred to as the "large case number." Depending on the era, this number may be engraved on the caseback, inside the case, or both. For the first 75 years of Audemars Piguet's history, the case number and movement number were identical because each movement was created specifically for the case that would house it.
This changed in the early 1950s, when Audemars Piguet modernized its production processes. Cases and movements were no longer paired one-to-one. Instead, the company began purchasing batches of pre-numbered cases from suppliers and matching them to movements during assembly. From that point on, case numbers became independent of movement numbers, and serial numbers advanced in their own sequence.
By the mid-1970s, AP had reached six-digit case numbers and introduced prefix letters, beginning with B, followed by numbers up to 99,999. (The earlier cases are considered to have an implied "A" prefix.) After B came C, then D, and so on. This system continued until 2017, when Audemars Piguet adopted randomized alphanumeric serial numbers to reduce counterfeiting and eliminate predictable production dating.
It's worth noting that, like movement numbers, Audemars Piguet case/serial numbers can estimate a rough production era, but they cannot date a watch precisely. This is particularly true of the modern randomized serial numbers, which can only confirm that the watch was produced in 2017 or later.
Serial Number Lookup Table
The Audemars Piguet serial number, also known as the "large case number," can help date the general production era of the watch. It is engraved on the caseback of the watch.
| Serial Range | Production Start | Production End (Approx) |
|---|---|---|
| 101 - 105,393 | 1951 | 1976 |
| B 1 - B 99,999 | 1975 | 1990 |
| C 1 - C 99,999 | 1984 | 1995 |
| D 1 - D 99,999 | 1991 | 2000 |
| E 1 - E 99,999 | 1998 | 2010 |
| F 1 - F 99,999 | 2003 | 2010 |
| G 1 - G 99,999 | 2009 | 2015 |
| H 1 - H 99,999 | 2011 | 2015 |
| I 1 - I 99,999 | 2013 | 2020 |
| J 1 - J 94,000 | 2015 | 2020 |
| Randomized | 2017 onwards | |
Royal Oak Serial Numbers: The Small Case Number
Audemars Piguet introduced a second numbering system specifically for the original Royal Oak 5402 in 1972. Because the company planned to produce 1,000 identical steel watches (a large number for the time), Managing Director Georges Golay elected to hide the standard case number inside the watch and instead engrave a large, easy-to-read serial on the outside. This became known as the small case number or Royal Oak number, beginning with A1 and increasing sequentially.
The A-series, comprising the first roughly 2,000 pieces (AP ultimately sold 1,937), is now one of the most famous serial ranges in watch collecting. Later came B-series, C-series, and D-series, each with its own production run and quirks. This system also shifted in the late 1970s and 1980s as gold and two-tone variants were added, which restarted numbering for each metal.
Around 1990, Audemars Piguet moved the large case number back to the exterior of the watch, where it appeared alongside the small Royal Oak number. Once sapphire-backed cases became more common, the small number shifted to the upper edge of the caseback.
By the late 2010s, as casebacks opened up and production varieties multiplied, the small Royal Oak number was phased out entirely. Today, modern Royal Oak watches — like all Audemars Piguet watches — use randomized alphanumeric case numbers with no visible small number codes.
What Today's Audemars Piguet Serial Numbers Tell You
- They're case numbers, not model or reference numbers.
- They're unique to each watch, a true serial number.
- They can give a general era of production, but not a precise year.
- They're essential for Extract requests, service records, and authentication.
- Since 2017, both case/serial and movement numbers are randomized alphanumerics.
Where to Find Audemars Piguet Serial Numbers
As noted above, on an Audemars Piguet watch, the serial number is the case number, and its location varies by era and model. Most modern AP watches feature the serial engraved on the caseback, either around the perimeter or on the solid back itself.
Earlier vintage pieces may have the case number engraved inside the case, which requires opening the watch to view it. Royal Oak models produced from the 1970s through roughly 1990 included the large case number on the inside of the caseback and the small Royal Oak number on the outside. Beginning in 1990, Royal Oak watches included both numbers on the exterior of the caseback. Since the late 2010s, Royal Oak models feature only the large case number — the true serial number — on the outside of the caseback.
In short, the serial number on any modern Audemars Piguet watch will be located on the caseback, clearly visible to those looking for it. The same number also appears on the watch's original paperwork, including the warranty card or Certificate of Authenticity, and should always match the number engraved on the case.
Why AP Serial Numbers Matter
Understanding Audemars Piguet serial and movement numbers is one of the most valuable skills a collector can develop. These identifiers help verify authenticity, establish a watch's production era, and provide essential information for service records or Extract requests. While neither number can pinpoint an exact production year (particularly since AP's move to randomized alphanumerics in 2017), together they offer meaningful insight into a watch's history.
Whether you're evaluating a Royal Oak, researching a vintage reference, or documenting your own collection, knowing how to locate and interpret these numbers ensures you have the most accurate picture of the Audemars Piguet timepiece in front of you.