Audemars Piguet has a continuous legacy of crafting exceptional calendar watches and continuously producing perpetual calendar watches, though for over a century, this complication remained almost exclusively reserved for pocket watches. The brand began selling its first full calendar wristwatches with moon phases in 1924, and according to its archives, the first perpetual calendar wristwatch was produced and delivered in 1955. Between 1924 and 1969, only 12 of the 208 calendar wristwatches delivered by AP featured a perpetual calendar—all of them crafted in 1955 and 1957 for the iconic reference 5516, the first wristwatch ever to display the leap-year cycle.

Introduced in 1978, reference 5548 featured calibre 2120/2800, the world’s thinnest automatic perpetual calendar movement at the time, measuring just 3.95 mm thick. This movement is the same one that powered the earliest Royal Oak Perpetual Calendars. Now, let me take you into the most complete history of the AP Royal Oak Perpetual Calendar.

The History of the Royal Oak Perpetual Calendar

The Beginning (1983 - 1995)

Only eleven years after the launch of the Royal Oak in 1972, the brand was already making history by releasing the iconic watch Royal Oak Perpetual Calendar complication. Fitted at the time with a 39 mm case—like the original Royal Oak 'Jumbo'—and powered by the automatic calibre 2120/2800, the Royal Oak Perpetual Calendar has seen many variations, limited editions, and case sizes throughout its history.

The first Royal Oak to feature a Perpetual Calendar complication was born in 1983 with the first sketches created in August of that year. The Royal Oak Perpetual Calendar reference 5554—later named 25554 when AP added the prefix ‘2’ to their reference numbers—included 49 pieces in stainless steel, 229 pieces in 18K yellow gold, and one unique piece in platinum. The Royal Oak Perpetual Calendar reference 25554 was sold to the public until the following year in 1984.

This first Royal Oak Perpetual Calendar was equipped with a monocoque—monohull—case carved from a solid single block of metal just like the Royal Oak Jumbo reference 5402 and powered by the calibre 2120/2800. Measuring just 3.95 mm in thickness, this calibre was among the thinnest in its category. However, it was 0.9 mm thicker than the calibre 2121 powering the Royal Oak Jumbo 5402.

To create additional space, the bezel height was increased by 0.6 mm, from 2.5 mm—including its 0.5 mm rubber gasket—to 3.1 mm and the sapphire crystal was dramatically reduced in thickness from 2 mm to just 0.9 mm, necessitating a shift from a heel-type attachment to a 45-degree domed bezel.

For the dial, the decision was made to forgo the usual ‘tapisserie’ pattern in favor of a cleaner aesthetic—and space-saving—with subdials that were hollowed out by 0.1 mm to accommodate the hands for the date, day, and month indications. Notably, the hour markers were refined to an ultra-thin profile, and the applied AP logo was omitted to maintain visual balance and, crucially, to avoid adding extra thickness.

The result was nothing short of exceptional: the Royal Oak Perpetual Calendar reference 25554 measured a mere 7.5 mm in total thickness—just 0.4 mm more than the Jumbo 5402—achieving a remarkable balance of technical innovation and aesthetic refinement.

The first 50 pieces in stainless steel of reference 25554 with what AP called a ‘crystal grey dial’ were reserved for the Italian market. At the time, Stephen Urquhart was leading Audemars Piguet and after 15 years with AP, he left in 1989 to take charge at JLC, Blancpain, and become the CEO of Omega in 1999. Below is the first picture of the Royal Oak Perpetual Calendar that accompanied the press release for the launch of the watch.

Photos Above: Audemars Piguet Archives

Today, there are no less than 25 different Royal Oak Perpetual Calendar references and more than 100 different models including grand complications in the Royal Oak family. While the first Royal Oak Perpetual Calendar reference 25554 was a true perpetual calendar in all the sense of the word—taking into account leap years—, its dial didn't feature a leap year indicator.

In 1985 the second reference in the history of the Royal Oak Perpetual Calendar was released as a one unique piece reference 25624BA in 18K yellow gold with diamonds on its bezel.

Photo Above: Audemars Piguet Archives

Then what we like to call the ‘official second Royal Oak QP reference’—in reality the third— was released in 1987 as Royal Oak Perpetual Calendar reference 25654 and produced until 1997. Most examples in this reference have a monocoque case that merged the case middle, case back and lugs into one piece component that was carved from a single block of steel or other materials. Approximately 851 examples of this reference left the Le Brassus workshops.

Different iterations of the Royal Oak Perpetual Calendar became available with up to seven metals in 18K yellow gold, .950 platinum, 18K rose gold with platinum bezel and platinum middle links, stainless steel, and even stainless steel stainless with a highly polished platinum bezel and platinum middle links on its stainless steel bracelet.

The Royal Oak Perpetual Calendar reference 25636 with a monocoque case was produced between 1986 and 1996 with 313 examples—130 in 18K yellow gold, 97 in stainless steel, 49 two-tone examples—24 in 18K rose gold with platinum, and 25 in steel and platinum—, 34 in platinum, and 3 in 18K rose gold.

It wasn’t until the late 1980s and early 1990s, that Audemars Piguet released open-worked examples of the Royal Oak Perpetual Calendar reference 25636 which was also equipped with a sapphire crystal display case back for those models. The production numbers for the Royal Oak Perpetual Calendar reference 25636 with a skeletonized dial and sapphire display case back include 8 examples in steel, 30 in 18K yellow gold, 7 in platinum, and 3 in 18K rose gold, making it one of the most rare ‘old school’ Royal Oak Perpetual Calendar watches ever released with a total of less than 50 watches ever produced.

In 1988, a full gem set Royal Oak Perpetual Calendar reference 25659 was released in 18K yellow gold with a diamond set case in a limited edition of 3 pieces and one in platinum. In 1989, the Royal Oak Perpetual Calendar reference 25688 was entirely covered with baguette-cut diamonds. The following year, the Royal Oak Perpetual Calendar reference 25694 featured a bezel adorned with diamonds and blue sapphires.

To celebrate the 20th anniversary of the Royal Oak, Audemars Piguet released a pair of Royal Oak Perpetual Calendar Pocket Watches—one in platinum and the other in 18K rose gold— in a limited edition of 20 pieces each with a case size of 47 mm, a skeletonized dial, and powered by the ultra-thin manual wound calibre 5020—fully skeletonized and hand engraved.

Photos: Audemars Piguet Archives

This release marked the first time that any Royal Oak included a leap-year indication; however, the year 1995 marks the ‘official’ year when the Royal Oak wristwatch was equipped with a leap-year indicator on its dial. Both pocket watches were accompanied by a fob chain matching the metal of the watch.

Photos Above: Ineichen Auction House

Before the official third reference was launched, another unique piece in 18K yellow gold was released as reference 25651. The official third reference released in 1987 in the Royal Oak Perpetual Calendar family was the reference 25654 and just like all previous 'Quantieme Perpetuel Automatique' Royal Oak watches, it still didn't feature the leap year information. Below is a chiselled ‘Tuscany Blue’ dial Royal Oak Perpetual Calendar reference 25654BA.

This particular Royal Oak Perpetual Calendar reference 25654—perhaps the second most popular with 800 pieces made—was released in different metal variations. All these examples no longer have a monocoque case construction but instead a tripartite case construction that includes a sapphire display case back.

Metals for this reference include stainless steel, .950 platinum, 18K yellow gold, tantalum with 18K rose gold bezel and center links—only 15 examples were made—, 18K rose gold with platinum bezel and platinum center links, and even a .950 platinum model with an 18K rose gold bezel and 18K rose gold center links on its platinum bracelet—pictured below and featured as a rare bird of this reference here. In 1994, the Royal Oak Perpetual Calendar reference 25775 was presented with a guilloché hobnail Clous de Paris bezel.

The Addition of a Leap-Year Indication (1995 - Early 2000s)

While all Royal Oak 'Quantième Perpétuel Automatique' watches didn't feature a leap year indicator until 1995, the movement on this complication was programmed mechanically to take automatic account of the occurrence of a leap-year—therefore, it had no issues switching from February 29 to March 1st on a leap-year.

Finally, in 1995, Audemars Piguet released a Royal Oak Perpetual Calendar with a leap-year indicator and also a peripheral 52-week indicator to commemorate its 120th anniversary. The 120th Anniversary Royal Oak Quantième Perpétuel ref. 25810OR.OO.0944.OR.01 was produced in 18K rose gold and available in a limited edition of 120 pieces bearing the inscription '1875-1995' on the moon phase indication and were all equipped with a fully gold-plated automatic movement.

Photo: Audemars Piguet Archives

Moving forward, all Audemars Piguet Royal Oak Perpetual Calendar watches included a leap year indication and were powered by the calibre 2120/2802. However, the 120th Anniversary Royal Oak Perpetual Calendar was the only one equipped with a week indicator until the year 2015 when the new reference 26574 was launched.

Then, circa 1996, another new Royal Oak Perpetual Calendar reference with several cases and dial variations became available under reference 25686 and was produced until around 1998-1999. The production of the Royal Oak Perpetual Calendar reference 25686 includes 92 pieces in steel, 70 pieces in 18K yellow gold, 18 pieces in 18K pink gold, 31 pieces in .950 platinum, 25 pieces in platinum and pink gold, 37 in 18K pink gold and platinum, 26 pieces in steel and .950 platinum for a total of 299 watches.

While up until 1996 the Royal Oak Perpetual Calendar was only available in a 39 mm case, that same year Audemars Piguet introduced a rare Royal Oak Perpetual Calendar reference 25800 featuring a 33 mm case that was intended to be a ladies’ watch but released as a men’s mid-size timepiece.

This Royal Oak Perpetual Calendar reference is the only one powered by the calibre 2141/2806 which also includes a leap year indicator on the dial. This release also marks the first time the Audemars Piguet Royal Oak Perpetual Calendar would become available in 18K white gold.

This reference is perhaps one of the most elusive ones—along with the tantalum examples of reference 25654—which was produced only in stainless steel, 18K white gold, 18K yellow gold, and .950 platinum. This reference lived for only a couple of years and then it was phased out due to its lack of popularity.

Photos Above: Sotheby’s

Then almost immediately after, the Royal Oak Perpetual Calendar reference 25820 was launched still powered by the calibre 2120/2802. The Royal Oak Perpetual Calendar reference 25820 marks the first use of ‘tapisserie’ dials on the Royal Oak Perpetual Calendar.

Before this reference, all other Royal Oak Perpetual Calendars were fitted with smooth dials. This reference was available with five dial variants in stainless steel —smooth silvered dial, white tapisserie, and three different blue tapisserie dials—, two dial variants in 18K yellow gold, two in platinum, three in stainless steel with platinum, and perhaps the most coveted of them all, tantalum and 18K rose gold version, tantalum and 18K yellow gold and the king of all Royal Oak Perpetual Calendars the tantalum and platinum version that is as rare as it gets.

In 1999, the Royal Oak Perpetual Calendar reference 25932BC is the second 18K white gold Royal Oak Perpetual Calendar ever made, this time set with 540 diamonds and with a wave guilloché dial.

Photo: Audemars Piguet Archives

The Modern Era (Early 2000s - 2025)

Years later seven new skeletonized—open-worked—Royal Oak Perpetual Calendars would make their appearance as reference 25829 in stainless steel, platinum, 18K yellow gold, 18K rose gold and once again the three ultra special tantalum combinations with platinum, rose gold, and yellow gold.

Alongside all these perpetual calendars, a family of new Royal Oak Grand Complications was released in the early 2000s including the Royal Oak Equation of Time Perpetual Calendar reference 26606 or the Royal Oak Grand Complication reference 25865 fitted with perpetual calendar, minute repeater, and chronographe rattrapante.

In 2008, the Audemars Piguet Royal Oak Perpetual Calendar was unveiled for the very first time on a leather strap and the Royal Oak Perpetual Calendar reference 26252 became available in two dial variants that included a white silvered dial as ref. 26262OR.OO.D092.CR.02 and a brown dial ref. 26262OR.OO.D092.CR.01. This reference was produced for six years and discontinued upon arrival of the new reference 26574.

The year 2015, marked a turning page for the Royal Oak Perpetual Calendar as it returned to the center stage with a brand new in-house calibre and four different iterations with white or blue dials and in stainless steel or 18K pink gold. The Royal Oak Perpetual Calendar reference 26574 was then born. Continuing with the shift in watch case sizes that began in 2012, the new Royal Oak Perpetual Calendar turned into a 41 mm watch—9.5 mm thick—instead of the classic 39 mm like all its predecessors since 1983.

The Royal Oak Perpetual Calendar reference 26574 was powered by the new in-house automatic calibre 5134 based on its predecessor the calibre 2120. However, this new calibre was enlarged by the updated 41 mm diameter case size. The highly finished 4.31 mm thick movement continues to be fully visible through the glare-proof sapphire crystal case back.

We also see that AP draws inspiration from the 120th AP Anniversary Royal Oak Perpetual Calendar ref. 25810OR.OO.0944.OR.01 and decides to add back the 52-week peripheral indication.

Beginning in 2018, several limited editions of the new Royal Oak Perpetual Calendar were presented and not all of them bear the same reference number. After releasing reference 26574, Audemars Piguet released another nine references including the 26579, 26584, 26585, 26586—the RD#2 world’s thinnest automatic perpetual calendar at just 6.30 mm thick in its prototype and regular production—, 26579, 26609, 26615, and 26613.

Notable editions include the first black ceramic Royal Oak Perpetual Calendar, first black ceramic open-worked perpetual calendar, the 50-piece limited edition in platinum with ice blue dial for Switzerland, the 100-piece in pink gold with pink-toned dial for Latin America, the 50-piece in stainless steel with a green dial for Hong Kong, the 88-piece in collaboration with Horoloupe in titanium with a slate grey dial with red accents for China, the 20-piece in platinum with black dial for Yoshida in Japan, the 20-piece in white gold with a red dial for Thailand, the 20-piece in platinum with sand-colored dial for the Time Place in Indonesia, the 75-piece UAE Limited Edition with a dial in the same color as the Abu Dhabi Yas Marina F1 circuit, the 300-piece titanium with salmon colored dial for Sediqqi, the Royal Oak Perpetual Calendar Cactus Jack in partnership with Travis Scott crafted in brown ceramic, the John Mayer Creative Conduit Perpetual Calendar, and the Royal Oak Perpetual Calendar Ultra-Thin Arabic Markers.

And yesterday, February 24, 2025, as part of its 150th Anniversary celebrations, Audemars Piguet introduced the new calibre 7138 to the Royal Oak Perpetual Calendar lineup after five years of R&D. This latest cutting-edge movement incorporates three patented mechanisms and allows the wearer to make all the perpetual calendar necessary adjustments via the crown, thus eliminating the need for any correctors or pushers around its case.

The new Royal Oak Perpetual Calendar reference 26674 is available in stainless steel as reference 26674ST.OO.1320ST.01 or in 18K Sand Gold as reference 26674SG.OO.1320SG.01. The new watches maintain the same case size proportions as its predecessors—references 26574, 26579, 26584, 26585, 26579, 26609, 26615, and 26613—at 41 mm in diameter and 9.5 mm in thickness. Both new watches continue to have a water resistance of up to 50 meters.

Looking at the layout of the previous iteration of the Royal Oak Perpetual Calendar reference 26574, you will notice that the date indication on the new reference has been moved to 12 o’clock, instead of 3 o’clock. Meanwhile, the month indication moved from 12 o’clock to 3 o’clock. Additionally, AP added a 24-hour indication on the day of the week subdial.

Along with these two new watches, AP celebrates its 150th anniversary with the Royal Oak 
Perpetual Calendar 150th Anniversary reference 26585XT.OO.1220XT.01 in a limited edition of 150 pieces in titanium with BMG—Bulk Metallic Glass— with a 41 mm case diameter and a thickness of 9.9 mm as a final tribute to the automatic Audemars Piguet calibre 5135 presented in 2015. The watch is equipped with a Royal Oak bracelet also in titanium with BMG—Bulk Metallic Glass—center links.

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