This year, Audemars Piguet commemorated its 150th anniversary by focusing on the iconic perpetual calendar, a watch from its long history of complicated watchmaking. The watch unveiled features a newly developed ultra-thin movement that dramatically enhances practicality. This innovative mechanism has taken the perpetual calendar into a new phase.
Photographs by Eiichi Okuyama
Text by Gisbert L. Bruner
Text by Gisbert L. Brunner
Edited by Yuzo Takeishi
[Article published in the July 2025 issue of Kronos Japan]
150 Years of Tradition and Innovation in Complicated Watches: The Ultimate Practical Perpetual Calendar
When watchmaker Jules-Louis Audemars set out on his own in the Vallée de Joux in 1875, the watches he produced already featured calendar displays. Fellow watchmaker Edouard-Auguste Piguet joined the company in 81, officially naming the company "Audemars Piguet." The two had great ambitions for complicated mechanical watches, particularly those with perpetual calendars from the start. Even they could never have imagined that 150 years later, the maison would remain in family hands and enjoy annual sales of over 20 billion Swiss francs. Under the family's successors, the first calendar wristwatch was created in 1921. However, the date still had to be manually corrected for months with fewer than 31 days.
その後、独立時計師アルフレッド・オーベールの支援を受け、57年までに計12本の複雑時計が製作された。中でも、Ref.5516に採用されたキャリバー13VZSSQPを搭載した9本は閏年表示で、そのうち3本は6時位置に48カ月表示を、6本は12時位置に世界初となる4年周期を示す針を備えていた。
In 78, the caliber 2120/2800 was installed in the reference 5548. It featured a perpetual calendar and moon phase display, but was only 3.95mm thick. It lacked a leap year indicator, but still set a precedent for other brands. In 97, the automatic caliber 2120/2802, measuring 4.05mm thick, was introduced. The addition of a leap year indicator made it easier to reset the movement after a long period of inactivity.
Then, in 2015, Audemars Piguet ushered in a new era of calendar displays with the introduction of the Caliber 5134. Based on the thoroughly improved Caliber 2120, it measured 4.31mm thick—0.26mm thicker than the 2120/2802—but this was due to a newly designed calendar mechanism and two new features. First, it displayed week numbers in accordance with ISO 8601, with the first Thursday of the year counted as week 1. Second, it featured a newly calculated moon phase display, achieving a high level of precision, with an error of just one day over the course of 125 years and 317 days.
The long-standing caliber 2120 also served as the basis for the world-record-setting calendar mechanism announced in 2018. Its 32mm diameter caliber 5133 made it possible to achieve a thickness of just 2.89mm thanks to the placement of the date, day of the week, month, leap year, and moon phase indicators on the dial side. The moon phase display boasts an accuracy that requires correction only once every 125 years, and a day/night indicator was added at 8 o'clock to facilitate calendar operation.
In 1922, the company released the Caliber 7121. This movement, which took five years to develop, used a unique switching wheel system for the winding mechanism and had a power reserve of approximately 55 hours. It also featured a variable inertia balance wheel and a flat balance spring, representing a significant advancement over previous models.
This year marks the 150th anniversary of Audemars Piguet's founding, and given that founder Jules-Louis Audemars was already working on the perpetual calendar mechanism in 1875, it's only natural that this complication should once again take center stage.
The latest Royal Oak Perpetual Calendar, now reduced to a 38mm diameter, is equipped with the new-generation automatic caliber 7136, further evolving the perpetual calendar mechanism. Its base is the caliber 7121, which lacks a date display, and incorporates the calendar mechanism into the dial. The caliber 7136 is an advanced version of the 5133, featuring a leap year indicator and a highly accurate moon phase display, and is 4.1mm thick. The revamped dial layout allows for intuitive reading, and all calendar operations can be performed using just the crown. Meanwhile, the caliber 7138, which powers the 41mm Royal Oak Perpetual Calendar, features a central hand indicating the week number.
These are all masterpieces of perpetual calendars that represent the forefront of technological innovation that Audemars Piguet has honed over its 150-year history, having specialised in complex mechanisms since its founding.
The exterior is made of sand gold, a proprietary material developed by Audemars Piguet and announced in 2024. It has a pale hue somewhere between pink and white gold. It is equipped with the Caliber 7138 movement and features a week display. It has automatic winding (Caliber 7138), 41 jewels, a frequency of 28,800 vph, and a power reserve of approximately 55 hours. The 18K sand gold case (41mm diameter, 9.5mm thick) is water resistant to 50m. Please inquire for pricing.
This cutting-edge watch features a perpetual calendar mechanism yet fits into a 38mm case. Like the 41mm perpetual calendar model released this year, the year, month, date, time, day of the week, and moon phase can all be adjusted by simply turning the crown. Automatic winding (Cal. 7136). 41 jewels. 28,800 vph. Power reserve: approximately 55 hours. 18KPG case (38mm diameter, 9.4mm thick). Water resistant to 50m. Price upon request.
https://www.audemarspiguet.com/com/ja/watch/2025-novelties.html
