Audemars Piguet Serial Number and Date Guide
An Audemars Piguet can carry several numbers. The reference identifies what configuration the watch is; case and movement numbers identify the individual watch in AP’s records; and some Royal Oaks also carry a separate public-facing individual number.
The charts below are AP’s approximate historical ranges. They overlap, estimate broad periods and never authenticate a watch or establish an exact production date by themselves.
AP uses several different numbering systems
| Identifier | Purpose | Typical location | Dating value |
|---|---|---|---|
| Model/reference number | Identifies a shared model or exact configuration. | Catalog, papers and product sheet; historically only rarely engraved. | Identifies configuration, not an individual date. |
| Big case number | Unique identifier for one case; commonly called the serial number in trade. | Outside or inside the case, depending on model and period. | Broad first-commercialization period before the randomized transition. |
| Movement number | Unique identifier for one movement. | Baseplate or bridge, usually requiring qualified access unless visible through the caseback. | Broad era only. |
| Small Royal Oak number | Separate owner-facing sequence introduced with the Royal Oak 5402. | Exterior caseback or model-specific exterior position. | Model/material-specific estimate only. |
| Calibre number | Identifies a movement design, such as 2121, 4302 or 4401. | Specifications and movement. | No individual dating value. |
Before approximately 1951, AP normally gave a watch’s case and movement the same number. From 1951, the big case number became independent of the movement number. A mismatch between modern case and movement numbers is therefore not automatically a problem; the numbers must be reconciled through the appropriate records.
AP big-case-number periods
| Big case number | Approximate period | Required interpretation |
|---|---|---|
| Unlettered 101–105393 | 1951–1976 | Do not call this a visible A-series; AP says the preceding cases were only tacitly associated with A. |
| B1–B99999 | 1975–1990 | This is the big case sequence, not automatically a Royal Oak 5402 B-series. |
| C1–C99999 | 1984–1995 | Overlaps adjacent series. |
| D1–D99999 | 1991–2000 | Broad first-commercialization period only. |
| E1–E99999 | 1998–2010 | Not one letter per calendar year. |
| F1–F99999 | 2003–2010 | Overlap is intentional. |
| G1–G99999 | 2009–2015 | Not sufficient for exact dating. |
| H1–H99999 | 2011–2015 | Not sufficient for authentication. |
| I1–I99999 | 2013–2020 | Check the character carefully; do not normalize it from seller text. |
| J1–J94000 | 2015–2020 | The chart is approximate and does not mean every number was used. |
| K / later alphanumeric | Transition began in 2017 | Modern assignment became randomized; K is not a fixed public year code. |
The ranges overlap because cases were not necessarily completed, cased, distributed and sold in strict numerical order. The letters also do not map cleanly to one year each. A case-range estimate should be phrased as “consistent with an approximate period,” never “made in exactly this year.”
AP movement-number periods
| Movement number | Approximate period | Movement number | Approximate period |
|---|---|---|---|
| 2000–4500 | 1880s | 4000–6500 | 1890s |
| 6000–14000 | 1900s | 11000–27000 | 1910s |
| 23000–42000 | 1920s | 41000–45000 | 1930s |
| 44000–60000 | 1940s | 55000–80000 | 1950s |
| 72000–120000 | 1960s | 110000–230000 | 1970s |
| 220000–350000 | 1980s | 330000–490000 | 1990s |
| 475000–750000 | 2000s | 700000–999999 | 2010–2017 |
AP’s oldest surviving production register begins in 1882 at movement number 2000. Not every number was used: AP notes that movement number 60000 represented only approximately the 30,000th movement produced. A numbered movement blank could also remain unfinished for years or decades before completion and casing.
After the numerical sequence approached one million, AP introduced alphanumeric movement identifiers. Modern alphanumeric values are not a public chronological lookup system.
The small Royal Oak number is not the case serial
When AP introduced the Royal Oak 5402 in 1972, the planned series of similar watches was unusually large for the manufacture. AP moved the technical big case number inside and engraved a separate, prominent owner-facing number on the exterior. Collectors call this the small Royal Oak number or small case number.
For the first steel 5402, the sequence used A, B, C and D series. Later Royal Oak models and precious-metal 5402 variants generally used model/material sequences without the same letter pattern. A small number can coexist with an entirely different big case number and movement number.
Royal Oak 5402 small-number chart
| 5402 configuration | Small Royal Oak number | Approximate period |
|---|---|---|
| 5402ST | A1–A500 | 1972–1973 |
| 5402ST | A500–A1000 | 1972–1974 |
| 5402ST | A1000–A1500 | 1973–1975 |
| 5402ST | A1500–A2000 | 1974–1976 |
| 5402ST | No small number | 1974–1976 |
| 5402ST | B1000–B1500 | 1975–1977 |
| 5402ST | B1500–B2000 | 1975–1977 |
| 5402ST | C1000–C1500 | 1976–1978 |
| 5402ST | C1500–C2000 | 1978–1980 |
| 5402ST | D1000–D1500 | 1979–1985 |
| 5402BA | 1–500 | 1977–1980 |
| 5402BA | 500–1000 | 1980–1986 |
| 5402SA | 1–500 | 1977–1980 |
| 5402SA | 500–1000 | 1979–1983 |
| 5402BC | 1–150 | 1977–1981 |
The number does not establish an exact production ordinal. AP documents unused numbers and non-sequential delivery. For example, one watch with a lower small number could be sold after another with a higher number. Say “consistent with this broad 5402 period,” not “the exact Nth Royal Oak made.”
This chart does not apply to every Royal Oak, every Offshore or generic AP case numbers. It is a model-specific interpretation of the 5402’s separate owner-facing sequence.
Why K-series and modern letters cannot produce an exact year
AP says that in 2017 it overhauled case and movement numbering and moved to randomized alphanumeric combinations to combat counterfeiting. K appeared during that transition, but it should not be published as a fixed one-year or clean multi-year date code.
Modern watches should be dated through the warranty record, invoice, AP account/service history and the watch’s documented chain—not an internet letter chart. A card year is a commercial documentation fact, not necessarily the same as component manufacture or assembly date.
What serial consistency can and cannot establish
A number outside every plausible range, a reference inconsistent with the case or records that conflict with the watch can be a warning. Conversely, a plausible or even genuine number can be copied onto a counterfeit or assembled watch. Matching papers can also be separated from their original watch.
AP’s own document policy is decisive:
- Extract from the Archives: confirms submitted case and movement numbers appear in AP records. AP says it does not warrant authenticity.
- Certificate of Authenticity: certifies the watch, materials and components after physical examination by AP experts in Le Brassus.
No public guide, seller database or image-only “serial lookup” can replace physical examination.
How to use AP numbers responsibly
- Identify whether the number is a reference, big case number, movement number, small Royal Oak number or calibre.
- Record the complete model reference and compare it with AP’s official product or archival material.
- Keep full individual numbers private and share them only with appropriate parties.
- Use historical charts only to test broad consistency, never to claim an exact year.
- Reconcile the physical watch, dial, case, bracelet or strap, clasp, movement and documentation.
- Check service and ownership records where available.
- Use qualified physical authentication and AP documentation when value or uncertainty warrants it.
For configuration decoding, continue to the AP reference-number guide. For physical inspection, use the condition and polishing guide.
Historical and modern AP records in context
These product pages intentionally show model references, not full individual case or movement numbers. Never publish a complete serial merely to support a guide.
Audemars Piguet serial-number and date FAQs
Can an AP serial number tell the exact year?
No. AP’s historical case and movement ranges overlap and estimate broad periods. Completion, casing, distribution and sale were not always sequential.
What is an AP K-series watch?
K appeared around AP’s 2017 transition to randomized alphanumeric case and movement identifiers. It is not a reliable fixed-year code.
Is the Royal Oak small number the same as the serial?
No. The small Royal Oak number is a separate owner-facing sequence. The big case number is the individual case identifier commonly called the serial in trade.
Where is the AP movement number?
It is engraved on a movement baseplate or bridge. Access may require opening the watch by a qualified professional unless the relevant engraving is visible through the factory caseback.
Does an AP Extract from the Archives prove authenticity?
No. AP says an extract confirms case and movement numbers appear in its records but does not warrant authenticity.
Can a seller’s serial-number photo authenticate the watch?
No. Plausible numbers can be copied, and genuine papers can be separated from a watch. Authentication requires reconciliation and physical examination.
Should I share a full AP serial number online?
No. Mask most digits in public listings, forums, guide examples and screenshots. Share complete unique numbers only with appropriate verification, service or transaction parties.
Sources and methodology
AP Chronicles: Audemars Piguet watch numbering · AP Chronicles: Royal Oak numbering · AP customer services and authenticity documents · AP Royal Oak 15510 reference example
Technical specifications and historical claims are checked against Audemars Piguet and AP Chronicles. Current price, imagery and availability are drawn from Superlative Watch Co.’s live Shopify product records.
Editorial review: July 27, 2026. Superlative Watch Co. is an independent luxury-watch dealer and is not affiliated with or authorized by Audemars Piguet. Product availability, pricing and specifications can change. Brand names and trademarks belong to their respective owners.