An Audemars Piguet reference number is a seventeen-character code like 15510ST.OO.1320ST.01, and it describes the watch completely: model, case material, bezel, bracelet and dial. Enter yours in the decoder below and it comes apart into plain English. The catch that trips most people up is that AP does not engrave the reference anywhere on the watch, so it lives on the warranty card and the certificate rather than on the case. The number engraved on your caseback is the case number, and unlike a Rolex serial it will not tell you what year the watch was made. Why that is, and what does date an AP, is covered further down.

The numbers on an Audemars Piguet

An Audemars Piguet carries two or three numbers, and they do different jobs. Mixing them up is the single most common mistake when buying, selling or describing one.

The important consequence: if you have the watch in your hand but not its paperwork, you do not have the reference number. You have a case number, which identifies that individual watch but tells you nothing about its configuration. Working out the reference means identifying the model from the watch itself, which is what the model code table and the generation timelines further down are for.

Anatomy of an Audemars Piguet reference

Every modern AP reference follows the same five-part structure. Take 15510ST.OO.1320ST.01 and read it left to right.

Two things worth knowing before you rely on the arithmetic. Vintage references from the 1970s and 1980s are shorter and do not always carry the full five segments. And the dial code is sequential rather than descriptive, so .01 is simply the first dial released for that model and .04 the fourth. There is no fixed colour attached to a dial number, and the same number means different things on different references.

Model codes

The first five digits are the part collectors actually use. Nobody says the full seventeen characters out loud. They say 15202, or 26420, and everyone knows what is meant. The code identifies the collection, the complication and the case size together, which is why a 41mm Royal Oak Selfwinding and a 37mm one carry different model codes despite looking almost identical in photographs.

Audemars Piguet reference database

Search by reference, model or nickname, or filter by family. Eighty-five references across the Royal Oak, Offshore, Code 11.59, Millenary, Jules Audemars and Concept lines, with the production window for each. Those windows are the most reliable dating tool available for an Audemars Piguet, because a reference that ran from 2012 to 2019 brackets the watch whatever the case number says.

Case material codes

The two letters immediately after the model code give the case material. AP uses abbreviated French in places, so OR is or rose, pink gold, rather than anything to do with the English word.

Bezel codes

The two letters after the first full stop describe the bezel. Most watches read OO, which simply means the bezel carries no stone setting or special finish.

Bracelet and strap codes

The third segment covers the bracelet or strap. Metal bracelets use four digits for the bracelet generation followed by two letters for its material. Straps use a letter-led code instead, so a code beginning with A or D is a strap rather than a bracelet.

The bracelet digits are a generation marker in their own right, and a useful cross-check. A 1320 bracelet did not exist before 2022, so a reference carrying one cannot be older than that.

Case number checker

Enter the number engraved on the caseback. The tool will tell you which numbering era it belongs to and what it can and cannot establish. It will not return a production year, because for an Audemars Piguet no honest tool can.

Why an Audemars Piguet cannot be dated from its serial number

Audemars Piguet has never published production data, and there is no collector-compiled case number chart comparable to the one that exists for Rolex. Any site offering an AP serial-to-year lookup is returning a number that is not grounded in published records.

What is documented is the shape of the system. Case numbers before 2017 were one letter followed by four or five digits, issued broadly in sequence. Collectors refer to these as series, so a D-series or an E-series watch, and the letters do correspond loosely to periods of production. The Offshore 25721 launched in 1993 as a D-series watch, and D-series production had already begun in 1992.

The problem is that those ranges were shared across the whole catalogue rather than reserved per model, and a series could run for years. A letter narrows a watch to a broad era at best, and the era is wide enough that the reference itself usually tells you more.

In 2017 Audemars Piguet moved to randomised case numbers, which closed the question entirely. A modern AP cannot be dated from the number on its caseback by anyone outside the manufacture.

How to date an Audemars Piguet

So the case number is the wrong tool. Five other things will get you close, in roughly this order of usefulness.

The reference production window. The strongest evidence and the easiest to check. A reference only existed between certain years, so it brackets the watch on its own. A 15400 is 2012 to 2019 and cannot be anything else. The database above gives the window for every reference on this page.

The calibre. Movements have their own production periods and AP changed them at known points. A calibre 4302 means 2019 or later. A calibre 2121 means the watch predates the 2022 changeover in the Jumbo line. If the movement postdates the reference, something needs explaining.

The warranty card. It carries a date, and it carries the reference number, which the watch itself does not. What it records is the date of sale rather than the date of manufacture, and the two can sit a year or more apart.

The bracelet generation. The four-digit bracelet code is a hard floor. A 1320 bracelet places the watch at 2022 or later. A 1240 bracelet belongs to the 15202 generation.

An extract from the archives. Audemars Piguet maintains records going back to the nineteenth century and will issue owners an extract for a watch on request. It is the only route to a manufacturer-confirmed production date, and it is a service the owner arranges directly with AP.

Audemars Piguet calibres

The calibre is stamped on the movement, which means a display caseback shows it and a solid one does not. Where you can read it, it is a strong cross-check on any claimed date.

Royal Oak generations

The Royal Oak has run continuously since 1972 and the generations are clean enough to date a watch by sight. Case size and movement are the two things that move.

Read that table backwards and it dates most Royal Oaks to within a few years without touching the case number. A 41mm steel Royal Oak with a 1320 bracelet and a calibre 4302 is a 15510, which means 2022 or later, and no other combination produces that result.

Royal Oak Offshore generations

The Offshore arrived in 1993 as a deliberate provocation: 42mm and roughly 16mm thick when the rest of the industry was making thin dress watches. The first hundred examples left Offshore off the caseback entirely, in case the model failed and the name could be reused elsewhere.

Audemars Piguet nicknames

Almost none of these are official and Audemars Piguet has never used one in its own literature. They stuck anyway, and in practice they are how these watches get discussed and searched for.

What a case number cannot tell you

A case number identifies one individual Audemars Piguet. That is the whole of what it does.

It does not give a production year, for the reasons set out above. It does not establish that a watch is genuine, because Audemars Piguet publishes no database the public can check a number against and numbers from real watches have been copied onto counterfeits. And it says nothing about whether the parts of the watch belong together, so a case can be original while the dial, bezel, bracelet or movement are not.

What holds up is consistency. A reference that matches the dial and bracelet in front of you, a calibre that matches the reference, a bracelet generation that matches both, and paperwork that agrees with all of it. Any one of those alone establishes very little.

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Glossary

The terms that come up most often when identifying or describing an Audemars Piguet.

Reference number

The seventeen-character model code that describes the watch. Not engraved on an AP, only documented on the card and certificate.

Case number

The number engraved on the caseback identifying that individual watch. Often called the serial. Does not give a production year.

Movement number

A separate number engraved on the movement mainplate, visible only through a display caseback.

Model code

The first five digits of a reference. The part collectors use in conversation.

Series

The letter at the start of a pre-2017 case number. Corresponds loosely to a period of production, shared across the catalogue.

Extract from the archives

A document Audemars Piguet issues to an owner confirming a watch's original specification and production date from the manufacture's own records.

Tapisserie

The squared waffle pattern on Royal Oak dials. Petite on the 39mm, Grande on 41mm and above, Mega on the 26420 Offshore.

Jumbo

The 39mm extra-thin Royal Oak line, from the 5402 to the 16202.

Offshore

The larger, chronograph-led Royal Oak line introduced in 1993.

Code 11.59

The collection introduced in 2019, an octagonal middle case inside a round bezel and caseback.

Frosted gold

A hammered Florentine finish applied to gold Royal Oak cases and bracelets. Carries the GG bezel code.

Openworked

Skeletonised, where the movement is cut away and visible through the dial.

Box and papers

The original packaging and documentation. On an AP the papers matter more than usual, because they carry the reference number.

Complete set

The watch together with its box, papers and accessories.

Unworn

Never worn. Not the same as new from an authorized dealer.

Calibre

The movement. AP identifies each by number and each has its own production window.

Frequently asked questions

How do I read an Audemars Piguet reference number?

Split it into five parts. A five-digit model code, a two-letter case material code, a two-letter bezel code, a bracelet or strap code, and a two-digit dial variant. So 15510ST.OO.1320ST.01 is a Royal Oak Selfwinding 41mm in stainless steel, standard bezel, 1320 steel bracelet, first dial version.

Where is the reference number on an Audemars Piguet?

It is not on the watch. Audemars Piguet does not engrave reference numbers on the case, unlike Rolex. The reference appears on the warranty card, the certificate of authenticity, service papers and product literature. The number engraved on the caseback is the case number, which is a different thing.

Where is the serial number on an Audemars Piguet?

The case number, which people usually call the serial, is engraved on the caseback. Depending on the model it can be on the outside, the inside, or both. There is often a separate movement number engraved on the mainplate, visible only through a display caseback.

What year is my Audemars Piguet?

It cannot be worked out from the case number. Use the reference production window instead, which brackets the watch to a known span of years, then narrow it with the calibre, the bracelet generation and the warranty card date.

Why can't an Audemars Piguet be dated by its serial number?

Audemars Piguet has never published production data, and no verified collector chart exists mapping case numbers to years. From 2017 the numbers were issued at random, which removed the possibility entirely. Any site offering an AP serial year lookup is producing a figure that is not grounded in published records.

What are AP letter series, like D-series or E-series?

Before 2017, case numbers were one letter followed by four or five digits, issued broadly in sequence. Collectors call each letter a series. They correspond loosely to periods of production, but the ranges were shared across the whole catalogue rather than reserved per model, so a letter narrows a watch to a wide era at best.

What does ST mean in an AP reference?

Stainless steel. The two letters after the model code give the case material. OR is pink gold, BA yellow gold, BC white gold, PT platinum, TI titanium and CE black ceramic.

What does OO mean in an AP reference number?

A standard, undecorated bezel. It is the most common bezel code by a wide margin. ZZ is a diamond-set bezel and GG the frosted hammered gold finish.

What do the last two digits of an AP reference mean?

The dial variant, numbered sequentially. The .01 is the first dial released for that model, .04 the fourth. The numbers are not tied to specific colours, and the same number means different things on different references.

What is the difference between the 15202 and the 16202?

Both are the 39mm Royal Oak Jumbo. The 15202 ran from 2000 to 2022 on the calibre 2121, the movement descended from the original 1972 Royal Oak. The 16202 replaced it in 2022 with the new calibre 7121, which added a quick-set date and a longer power reserve.

What is the difference between the 15400, 15500 and 15510?

All three are the 41mm Royal Oak Selfwinding. The 15400 ran 2012 to 2019 on the calibre 3120. The 15500 replaced it in 2019 with the calibre 4302, wider indexes and a repositioned date. The 15510 arrived in 2022 with refined case geometry and the 1320 bracelet.

Which Royal Oak is the Jumbo?

The 39mm extra-thin line: the original 5402 from 1972, then the 14802, 15002, 15202 and the current 16202. The nickname dates from 1972, when a 39mm steel watch was considered enormous.

Which Offshore is the Beast?

The 25721ST, the first Royal Oak Offshore, launched in 1993 at 42mm and roughly 16mm thick. The first hundred examples left the word Offshore off the caseback.

What is the Safari Offshore?

Reference 26470ST.OO.A801CR.01, a 42mm Offshore chronograph with a cream dial on a brown alligator strap.

What is the difference between Grande and Petite Tapisserie?

The size of the squared waffle pattern on the dial. Petite Tapisserie is the finer version used on the 39mm Jumbo, Grande Tapisserie the larger pattern on 41mm and above, and Mega Tapisserie the largest, introduced on the 26420 Offshore in 2021.

What does the bracelet code in an AP reference tell me?

The generation and material of the bracelet, and by extension a date floor. A 1320 bracelet was introduced in 2022, so a reference carrying one cannot be older. A code beginning with a letter is a strap rather than a metal bracelet.

Does the warranty card show when an AP was made?

It shows when the watch was sold, which can be a year or more after it was made. It is still valuable, because it is one of the few places the reference number appears in writing.

Can Audemars Piguet tell me when my watch was made?

Yes. Audemars Piguet keeps records going back to the nineteenth century and will issue an owner an extract from the archives for a watch. It is the only route to a manufacturer-confirmed production date, and the owner arranges it directly with AP.

Is the case number proof that an Audemars Piguet is real?

No. There is no public database to check it against, numbers from genuine watches have been copied onto counterfeits, and a case number says nothing about whether the dial, bezel, bracelet and movement belong with the case. Dating and authentication are separate questions.

What if my Audemars Piguet has no box or papers?

Then the watch has to identify itself. Case size, bezel, dial pattern, bracelet generation and the calibre together will usually pin down the reference, and the reference gives you the production window. The model code table and the generation timelines on this page are built for exactly that.

Who buys Audemars Piguet watches in Louisiana?

Watch The Throne Timepieces buys Audemars Piguet from Baton Rouge and across Louisiana, including New Orleans, Lafayette, Prairieville and Gonzales, as an independent specialist rather than an authorized dealer. Send the reference and the condition and you will get a real number back.

Buying, selling or hunting an Audemars Piguet