The most complete AP serial number reference online — full vintage production tables from 1892 to 1975, the complete A–K letter series with dates, a position-by-position reference number decoder, and a practical authentication checklist.
Audemars Piguet has used three distinct serial systems across its history. 1892–1975 (vintage numeric): sequential numbers you can date precisely using the production tables below. 1975–2019 (letter series): alphanumeric codes beginning with a letter (A through K) that changes after every 100,000 watches — dateable to an approximate 2–3 year window. 2019–present (randomized): deliberately non-sequential; the serial alone cannot date the watch. Throughout all eras, AP also assigns a separate movement number engraved on the calibre mainplate. The reference number — found only on paperwork, not the watch itself — is a 17-character code that encodes model, material, bezel, bracelet, and dial in a fixed positional format.
- The Three Eras of AP Serial Numbers
- Where to Find the Serial Number
- Vintage Production Tables (1892–1949)
- Vintage Production Tables (1950–1975)
- The Letter Series (A–K, 1975–2019)
- The Randomized Era (2019–Present)
- Movement Numbers: A Separate System
- The “No” Production Number
- Reference Number: Full Decoder
- Authentication: Genuine vs. Fake
- Official Verification & Archives
- FAQs
The Three Eras of AP Serial Numbers
Before reaching for any table, identify which era your watch belongs to. The system AP used during each period is fundamentally different — using the wrong approach will produce a wrong or meaningless result.
The transition from numeric to letter-series serials began with the Royal Oak’s introduction in 1972, when the A series was introduced for new references. However, older numeric serials continued to be used on existing production through approximately 1975. You may encounter watches from 1972–1975 carrying either a numeric or an A-series alphanumeric serial. This overlap is normal. Similarly, the shift to randomized serials in late 2019 was gradual — some sequential J-series numbers continued to be assigned into early 2020.
Where to Find the Serial Number
The location of the serial — officially called the case number by Audemars Piguet — varies meaningfully by era and by model. Knowing where to look before you start examining the watch saves time and prevents confusion with other engraved numbers.
Royal Oak — Model-Specific Location Notes
The Royal Oak has a well-documented evolution in where AP placed its case numbers across production generations:
| Period | Case Number Location | Additional Engraving |
|---|---|---|
| 1972 – ~1990 | Inside caseback (requires opening) | Small Royal Oak production number visible on exterior of caseback |
| ~1990 – ~2017 | Exterior of caseback | “No” production number also on exterior above case number |
| 2017 – Present | Exterior of caseback only | “No” production number discontinued in 2017 |
Vintage Serial Number Dating Table: 1892–1949
For the first 83 years of production, Audemars Piguet used a single sequential numeric system that runs continuously from the brand’s founding through 1949. These ranges are sourced from Audemars Piguet: Masterpieces of Classical Watchmaking (Brunner, 1993) — the definitive primary source for AP vintage serial research.
Until approximately 1951–1952, the case serial and movement number on an Audemars Piguet were identical — each movement was made for its specific case, so only one number existed. After this point, the two numbers diverge. On watches from this era, the serial is engraved on the movement mainplate and requires opening the watch to read. Dating is accurate to within approximately one calendar year for this period.
| Year | Serial Number Range | Year | Serial Number Range |
|---|---|---|---|
| Founding Era — Jules Louis Audemars and Edward Auguste Piguet establish the manufacture in Le Brassus | |||
| 1892 | 4,341 – 4,505 | 1893 | 4,506 – 5,196 |
| 1894 | 5,197 – 5,436 | 1895 | 5,437 – 5,620 |
| 1896 | 5,621 – 5,773 | 1897 | 5,774 – 5,990 |
| 1898 | 5,991 – 6,104 | 1899 | 6,105 – 6,294 |
| 1900 | 6,295 – 6,724 | 1901 | 6,725 – 6,933 |
| Early 20th Century — Pocket watch movements predominate; production grows steadily each decade | |||
| 1902 | 6,934 – 7,892 | 1903 | 7,893 – 8,717 |
| 1904 | 8,718 – 9,511 | 1905 | 9,512 – 10,219 |
| 1906 | 10,220 – 11,575 | 1907 | 11,576 – 11,825 |
| 1908 | 11,826 – 12,630 | 1909 | 12,631 – 12,851 |
| 1910 | 12,852 – 13,762 | 1911 | 13,763 – 14,735 |
| 1912 | 14,736 – 15,589 | 1913 | 15,590 – 16,675 |
| 1914 | 16,676 – 16,930 | 1915 | 16,931 – 17,725 |
| 1916 | 17,726 – 19,524 | 1917 | 19,525 – 20,915 |
| 1918 | 20,916 – 22,925 | 1919 | 22,926 – 24,804 |
| Interwar Period — Wristwatch production begins in earnest; production significantly disrupted by the Depression (1930–1936) | |||
| 1920 | 24,805 – 27,584 | 1921 | 27,585 – 28,820 |
| 1922 | 28,821 – 29,704 | 1923 | 29,705 – 30,673 |
| 1924 | 30,674 – 32,713 | 1925 | 32,714 – 34,505 |
| 1926 | 34,506 – 36,849 | 1927 | 36,850 – 38,576 |
| 1928 | 38,577 – 39,844 | 1929 | 39,845 – 41,577 |
| 1930 | 41,578 – 42,531 | 1931 | 42,532 – 42,585 |
| 1932 | 42,586 – 42,587 | 1933 | 42,588 – 42,626 |
| 1934 | 42,627 – 42,659 | 1935 | 42,660 – 42,776 |
| 1936 | 42,777 – 42,874 | 1937 | 42,875 – 43,785 |
| 1938 | 43,786 – 43,950 | 1939 | 43,951 – 44,647 |
| WWII & Postwar — Swiss manufacture benefits from wartime demand for precision instruments; AP production grows steadily into the 1950s | |||
| 1940 | 44,648 – 44,935 | 1941 | 44,936 – 45,655 |
| 1942 | 45,656 – 46,551 | 1943 | 46,552 – 47,541 |
| 1944 | 47,542 – 47,949 | 1945 | 47,950 – 49,595 |
| 1946 | 49,596 – 51,613 | 1947 | 51,614 – 53,517 |
| 1948 | 53,518 – 55,550 | 1949 | 55,551 – 56,704 |
These ranges are accurate to within approximately one calendar year. Note that in the early 20th century, only roughly half the numbers in a given range were actually allocated — AP held back blocks for later use. Additionally, movements were often numbered when the blank was acquired from a parts supplier, not when the watch was completed, so date-of-production can lag the serial’s implied year by six months to over a year. For legal or insurance purposes, only Audemars Piguet’s archive service can provide a confirmed production date.
Vintage Serial Number Dating Table: 1950–1975
From 1950 onward, AP began assigning different serial number blocks to different movement calibre families within the same production year. This means the ranges for 1950–1975 are segmented by calibre type rather than forming a single continuous run.
The principal vintage calibres from this era and their series designators include the 2001, 2003, 2005, 2050 (the legendary ultra-thin manually wound calibre), 2120 (the first ultra-thin automatic, 2.45mm), 2121 (the calibre that powered the original Royal Oak), 2430, 2510, 5017, and various Valjoux-based chronograph movements (13″‘ VZSS, VZSSC). Each calibre family received its own serial blocks each year.
The table below shows the summary-level top end of each year’s numeric range — sufficient to place a watch in the correct year for most purposes. Collectors researching a specific calibre within this period should consult the full Stetz & Co. reference database (sourcing Brunner 1993), which documents every block by movement type.
| Year | Overall Serial Range (all calibres) | Key Models & Notes |
|---|---|---|
| 1950 | 56,705 – 57,014 | Multiple calibre blocks within this range |
| 1951 | 57,015 – 57,408 | Cal. 9ML, 9/10RS, Valjoux active |
| 1952 | 57,409 – 61,395 | First Valjoux chronographs (13″ VZSS); new 6xxxx block opens |
| 1953 | 58,000 – 63,552 | Cal. 2001, 2002, 2003, 2499 blocks active |
| 1954 | 58,700 – 63,800 | Multiple LeC (Lecoultre) calibre families |
| 1955 | 59,200 – 66,234 | JVEB, JVB movements appear; Cal. 2499 active |
| 1956 | 53,800 – 69,360 | Ranges become highly non-contiguous across calibres |
| 1957 | 59,900 – 73,020 | VZSS, VZSSQP chronographs produced |
| 1958 | 62,356 – 73,770 | First documented AP Tourbillon (s/n 64803) |
| 1959 | 66,237 – 80,170 | Cal. 2070, 2071 (thin movements) active |
| 1960 | 69,561 – 80,070 | Cal. 2426 introduced; thin movement production expands |
| 1961 | 69,761 – 85,900 | Cal. 2050, 2072 range opens |
| 1962 | 82,301 – 91,500 | Cal. 2050 ultra-thin prominent; 2426 blocks |
| 1963 | 83,301 – 94,100 | |
| 1964 | 86,501 – 95,700 | |
| 1965 | 86,001 – 99,211 | Serials approaching six figures |
| 1966 | 85,301 – 102,640 | Serials cross 100,000 |
| 1967 | 96,201 – 107,370 | Cal. 2120 (ultra-thin automatic, 2.45mm) introduced |
| 1968 | 85,401 – 109,870 | Cal. 2120 and 2121 production scaling |
| 1969 | 85,501 – 116,700 | |
| 1970 | 111,801 – 131,100 | Cal. 2430 (ultra-thin manual) active |
| 1971 | 118,701 – 131,400 | Cal. 5017; Cal. 2121 scaling for Royal Oak |
| 1972 | 110,171 – 139,400 | Royal Oak ref. 5402 introduced (April 1972) — Cal. 2121 |
| 1973 | 120,818 – 154,200 | Royal Oak production ramps; Cal. 2510 appears |
| 1974 | 143,301 – 164,900 | |
| 1975 | 151,301 – 175,500 | Final year of purely numeric system; A-series letter serials begin |
Because 1950–1975 serials are not contiguous across all calibres, a number may appear to fall “between” two years in the table above. This is expected — the block was assigned to a different calibre family running concurrently. If your vintage serial falls in this range and you need precise confirmation, cross-reference the Brunner tables by calibre designation or submit an Extract from Archives request to Audemars Piguet directly.
The Letter Series (A–K): 1975–2019
Beginning in 1975 (with A-series serials having appeared on Royal Oak references since 1972), Audemars Piguet standardised a new approach: every case serial begins with a letter, followed by a sequence of digits. The letter changes after every 100,000 watches produced. At AP’s production volume of approximately 40,000 watches per year, each letter covers roughly two and a half to three years of output.
Because AP has never officially published its serial tables, all dates below reflect collector-compiled data sourced from Rolexforums and corroborated by specialist databases. Treat them as approximate production windows, accurate to within one to two years.
| Series | Approximate Production Years | Notes |
|---|---|---|
| A | 1972 – 1975 | Introduced with the Royal Oak ref. 5402; coexists with numeric serials through 1975 |
| B | 1976 – 1979 | Covers the early post-Royal Oak expansion era |
| C | 1980 – 1986 | Longer window reflects lower production volume during early 1980s |
| D | 1987 – 1994 | Royal Oak Offshore concept developed; expanded ref. lineup |
| E | 1994 – 2000 | Royal Oak Offshore ref. 25721 (1993); strong growth through late 1990s |
| F | 2001 – 2007 | AP enters strong commercial period; limited editions proliferate |
| G | 2008 – 2010 | Shorter window as production volume grows; annual output approaching 40,000 |
| H | 2011 – 2012 | Approximately 2.5 year window per letter now standard |
| I | 2013 – 2015 | In-house Calibre 3120 and 3126 production; RO 15400 active |
| J | 2016 – 2019 | “No” production number discontinued in 2017; randomization begins late 2019 |
| K | 2017 – 2019 | K series introduced alongside J; marks transition period into full randomization |
On AP watches produced from approximately the 1990s through 2017, you will find an additional engraving on the caseback that begins with “No” followed by digits (e.g., No 0342). This is the production sequence number — it tells you this watch was the 342nd unit of that specific model in that specific metal produced. It is not the serial number. Audemars Piguet discontinued this engraving on new production around 2017 with the J series. Its presence is a helpful authenticity marker on watches from its active period.
The Randomized Era (Late 2019–Present)
In approximately the fourth quarter of 2019, Audemars Piguet stopped assigning sequential case numbers and switched to a deliberately randomized alphanumeric format. The change was security-driven: a predictable sequence allows bad actors to fabricate plausible-looking serials. With randomization, no one outside AP can generate a valid-looking number.
For owners and buyers of modern AP watches, this means the serial number alone cannot be used to establish production year. The tools available are:
- Audemars Piguet My AP app / online registration: Activating the digital warranty card records the date of sale. This establishes when the watch was sold, not when it was made — typically within 6–18 months of manufacture.
- Reference number: The first five digits encode the model. Cross-referencing with AP’s public catalogue establishes when a given reference was introduced, providing a lower bound on the production date.
- Extract from the Archives: The only way to get a confirmed, official production date directly from AP’s records.
Movement Numbers: A Separate System
Every Audemars Piguet watch carries two distinct numbers: the case number (serial, on the caseback) and the movement number (on the mainplate of the calibre itself). These are entirely separate and serve different purposes. Confusing them is one of the most common errors in AP identification.
| Feature | Case Number (Serial) | Movement Number |
|---|---|---|
| Location | Outside (or inside) of caseback | Engraved on movement mainplate — requires opening the case or a transparent caseback |
| What it identifies | The individual watch as a complete unit | The specific calibre movement — engine, complications, and function |
| Format | Numeric (pre-1975) or alphanumeric (post-1975) | Numeric up to 999,988 — then AA0001, AA9999, AB0001… (never reaches 1,000,000) |
| Historic records start | 1892 (case number 4,341) | 1882 (Production Register, beginning at movement 2,000) |
| Can date the watch? | Yes (pre-1975 numeric); Approximately (A–K letter series); No (post-2019) | Yes — independently, using AP’s movement production registers |
| Why it matters for authentication | Confirms the watch is registered in AP records | Cross-checking case + movement numbers verifies the watch hasn’t been frankensteined — mismatching eras or calibres is a red flag |
The movement number is what forensic authentication focuses on when evaluating whether the movement inside a watch is period-correct for the case. A D-series case (1987–1994) fitted with a movement numbered from the 2010s, for example, signals a replacement or a case swap.
The “No” Production Number
Separate from both the serial and movement number, some Audemars Piguet watches carry a sequential production number on the caseback preceded by the abbreviation “No” (e.g., No 0342 or No 1500). This small but important marking tells you which unit of that specific model configuration the watch was — the 342nd Royal Oak 15400ST with a blue dial produced in that configuration, for example.
This number was engraved on the exterior caseback from approximately the early 1990s onward. Audemars Piguet discontinued the “No” engraving in 2017 when the J series was introduced. Its absence on a watch claiming to be pre-2017 can be a soft authentication flag depending on the reference. Its presence on a post-2017 watch, conversely, would be unusual and worth scrutinising.
Audemars Piguet Reference Number: The Full Decoder
The AP reference number is a 17-character alphanumeric code that encodes five pieces of information in a fixed position structure. Critically, it is not engraved on the watch itself — it appears only on the accompanying paperwork (warranty card, certificate of authenticity) or in official AP documentation. When buying or selling, this number should always match across the physical watch, the paperwork, and any listed specifications.
Worked Example: 15400ST.OO.1220ST.02 (Royal Oak Selfwinding, Steel)
Case Material Codes (Segment 2)
| Code | Material | Code | Material |
|---|---|---|---|
| ST | Stainless Steel (316L) | OR | 18k Rose Gold |
| BA | 18k Yellow Gold | RO | Rose Gold & Ceramic |
| BC | 18k White Gold | SA | Steel & Yellow Gold |
| PT | Platinum | SR | Steel & Rose Gold |
| TI | Titanium | SO | Steel & Ceramic |
| CB | White Ceramic | IO | Titanium & Ceramic |
| CE | Black Ceramic | FR | Forged Carbon |
Bracelet & Strap Codes (Additional Letters in Segment 4)
| Code | Material | Code | Material |
|---|---|---|---|
| CA | Rubber strap | VE | Calfskin strap |
| CR | Leather strap | KB | Rubber-coated strap |
| Metal bracelets use same code as case material (ST, BA, OR, etc.) | |||
The first two digits of AP model numbers map to collections: 15xxx = Royal Oak selfwinding (e.g., 15400, 15202, 15510). 26xxx = Royal Oak Offshore (e.g., 26420, 26237). 77xxx = Millenary (e.g., 77247). 67xxx = Royal Oak Lady. The specific five-digit number within each family further narrows the case size, complication, and generation. This is the most reliable way to identify the exact model when a watch is separated from its paperwork.
Authentication: Genuine vs. Fake
Audemars Piguet — and the Royal Oak in particular — is among the most heavily counterfeited names in luxury watches. High-quality fakes now replicate case engravings convincingly. Serial and reference numbers are an important first checkpoint, but cannot authenticate a watch on their own. Use them as part of a comprehensive assessment.
- Serial letter matches the claimed production era — a C-series serial (1980–1986) on a Royal Oak 15400 (introduced 2012) is impossible
- Deep, machine-precise engraving with consistent depth and font weight throughout; characters do not look stamped
- “No” production number present on watches from approximately 1990–2017; absent on those before or after
- Case number and movement number are period-correct relative to each other — no era mismatch
- Reference number on papers matches exactly what the physical watch spec should be (model no., material, bezel, bracelet)
- Royal Oak caseback location of serial matches the expected location for the production era
- Movement visible through caseback (if applicable) shows correct calibre and AP finishing quality
- Serial letter is inconsistent with the claimed model or year — a D-series (1987–1994) serial on a “2019” AP
- Shallow, uneven, or laser-etched-looking engraving — genuine AP engravings are crisp and deep
- “No” production number present on a post-2017 watch, or missing on a reference that should carry it
- Serial number that appears in multiple listings online — counterfeiters recycle known valid serials
- Reference number on papers does not correspond to the physical watch’s visible specifications
- Caseback location of serial inconsistent with claimed production era (e.g., exterior serial on a claimed 1985 Royal Oak)
- Movement shows a different calibre designation than the reference specifies
A serial number alone — even one that checks out on every list — cannot authenticate an Audemars Piguet. Sophisticated fakes copy valid serial numbers from authenticated watches. Full authentication requires physical examination of movement quality, case finishing, dial printing, crown and pushers, and the complete reference number against the documented specification. For any Royal Oak above $15,000, an examination by an AP boutique, authorised service centre, or certified independent specialist is worth the cost.
Official Verification & the Extract from the Archives
For definitive authentication, production records, or provenance documentation, Audemars Piguet maintains official channels. The most important is the Extract from the Archives — a document AP issues that confirms a watch’s production year, reference, and original specification based on their internal records.
- Audemars Piguet Boutiques: Submit the watch in person at any AP boutique worldwide. The boutique will send it to Le Brassus for examination if needed. This is the most reliable path.
- Authorised Service Centres: Can run a serial check and initiate an Extract request on your behalf.
- AP Heritage / Archive Service: Audemars Piguet’s heritage team in Le Brassus. Contact via audemarspiguet.com/services. Extract from Archives is available for a fee.
- My AP App / Online Registration: Confirms date of sale activation for modern watches (post-2019). Does not provide production date.
For vintage pieces where records may be incomplete, the specialist collector community — particularly the AP Talk section of Watchuseek and dedicated vintage AP forums — often has deeper reference-specific knowledge than official channels for production dating questions.
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Get a Free AP Appraisal →Frequently Asked Questions
Where is the serial number on an Audemars Piguet watch?
On modern AP watches (post-1990), it is engraved on the exterior of the caseback. On early Royal Oaks (1972–~1990), it is engraved inside the caseback and requires a watchmaker to open the case. On vintage watches from before approximately 1952, the serial and movement number were identical and appear on the movement mainplate itself. The serial can also be found on the warranty card or certificate of authenticity.
Can I date my Audemars Piguet from the serial number alone?
It depends on the era. Pre-1975 numeric serials can be dated to within one calendar year using the tables above. Letter-series serials (A–K, 1975–2019) date to within approximately 2–3 years. Post-2019 randomized serials cannot be used to date the watch at all — you’ll need an Extract from the Archives or to register the watch through the My AP app to establish when it was sold.
What is the difference between the case number and the movement number?
The case number (serial) is unique to the watch’s housing and is engraved on the caseback. The movement number is unique to the calibre inside and is engraved on the movement’s mainplate. Before approximately 1952, they were the same number. After that, they are separate. Both appear in AP’s production records and both should be period-correct relative to each other on an authentic watch.
What does the “No” number on the caseback mean?
It is the sequential production number for that specific model and metal combination — for example, the 342nd Royal Oak 15400ST produced in that configuration. It is separate from the serial number. Audemars Piguet discontinued this engraving in 2017 when the J series was introduced. Its presence helps date and authenticate watches from the 1990s through 2017.
Where is the reference number on an Audemars Piguet?
Audemars Piguet does not engrave the reference number on the watch itself. It appears only on the accompanying paperwork — the warranty card, certificate, or other official documentation. This is a key difference from Rolex (which engraves the reference between the lugs) and Breitling (which engravies it on the caseback). Always verify the reference on paper against the physical watch’s specifications.
Why did Audemars Piguet switch to randomized serial numbers?
Security. A predictable sequential system allows counterfeiters to generate plausible-sounding serials. With a randomized format, no external party can produce a valid-appearing number. The shift, which began with the K series around 2017 and became standard in Q4 2019, also makes it harder to deduce production volumes or timelines from the serial alone.
How do I get an official Audemars Piguet Extract from the Archives?
Contact Audemars Piguet through any official boutique or authorised dealer, or submit a request directly through the AP heritage service at audemarspiguet.com. You’ll need the serial number and, where available, the reference number and documentation. The Extract confirms the watch’s production year, original reference, and specification as AP records it. There is a fee for this service.
Quick Reference: Which System to Use
| Your Watch Era | How to Date It | Reference Number Location |
|---|---|---|
| Pre-1950 (numeric serial) | Use 1892–1949 table above. Accurate to ~1 year. | Vintage references are 3–4 digit model numbers; found on paperwork |
| 1950–1975 (numeric, multi-calibre) | Use 1950–1975 summary table; cross-reference by calibre type for precision. | Same as above |
| 1975–2019 (letter series A–K) | Identify the leading letter, consult the letter series table. Accurate to ~2–3 years. | 17-character reference on paperwork (e.g., 15400ST.OO.1220ST.02) |
| 2019–Present (randomized) | Serial cannot date the watch. Register on My AP app for sale date; request Extract for production date. | 17-character reference on paperwork; model number family (15xxx, 26xxx) identifies collection |
Le Watch Buyers · Watch Education & Blog Series · lewatchbuyers.com · Vintage serial number tables sourced from Audemars Piguet: Masterpieces of Classical Watchmaking (Brunner, 1993), corroborated by Stetz & Co. reference database. Letter-series dates reflect collector-compiled approximations originally published on Rolexforums — not official AP data. All serial and reference number information is provided for educational and identification purposes only. For insurance, legal, or high-stakes transaction authentication, obtain an official Extract from the Archives directly from Audemars Piguet SA.