Leap Year Luxury: Modern Masters of the Perpetual Calendar

Pushing boundaries in design, construction, and functionality.

It’s that time of year again, or rather, once every four years! Twenty-twenty-four is a year that will excite all watch enthusiasts, especially those who own perpetual calendar watches. For the first time in four years, February 29th graces us with its presence.

 

To merely label this moment as exciting would be an understatement. Perpetual calendars stand among the most captivating complications for watches – perhaps even mind-blowing upon first encounter. They possess the ability to mechanically program various calendar cycles, determining which days to skip and which to acknowledge. Today, as February 29 graces us with its presence, we commemorate the culmination of the longest cycle within a perpetual calendar – the four-year leap year cycle.

 

As watch enthusiasts approach this exciting event, it’s natural to seek out videos showcasing perpetual calendar watches in action, articles on the history of the complication, or even the pursuit of owning a perpetual calendar wristwatch! And that’s the focus of this story: to curate and present the best examples to our readers, but with a unique approach.

Patek Philippe 97975: The first wristwatch with perpetual calendar (©Revolution)
Patek Philippe 97975: The first wristwatch with perpetual calendar (©Revolution)

The history of perpetual calendar wristwatches is well-documented, with pioneers like Audemars Piguet, Patek Philippe, and Breguet laying the foundation. Their achievements are undeniable, but innovation continues to flourish. Modern names like H. Moser & Cie. with its forward-backward setting and instantaneous jumping functionality, IWC’s user-friendly single-crown interface, and Ludwig Oechslin’s ingeniously simple nine-part module all contribute their unique perspectives to the ongoing legacy of perpetual calendars.

 

Whether it’s the pioneers or the innovators, their stories and watches have become ingrained in horological lore. Therefore, our focus shifts to the exciting world of recently released perpetual calendar watches. We’ve specifically narrowed our search to those launched since the last leap year, four years ago. We’ve selected five modern and innovative examples with beautiful designs and executions, both in dial and movement. These timepieces offer the potential to become future classics, and you can own one today. Here’s our list!

The unusual yet classical: Patek Philippe In-Line Perpetual Calendar Ref. 5236P

First on our list is a design standout. Its calendar layout is remarkably simple, clean, and legible, unlike any other offering in the market. It also carries a touch of historical excitement. This is the Patek Philippe In-Line Perpetual Calendar Ref. 5236P, launched in 2021 right after the olive-green Nautilus, a move arguably showcasing the brand’s mastery of complications.

 

The Ref. 5236 draws inspiration from a historical Patek Philippe example, the Ref. 725/4 pocket watch, which also presented the date, day, and month at 12 o’clock, aligned horizontally – hence the “in-line” moniker. However, it wasn’t simply a miniaturized version of the pocket watch movement because the original mechanism was too large for a wristwatch. Miniaturization alone would result in an unreadable display.

The Patek Philippe Reference 5236P is the world’s first single aperture perpetual calendar with an inline display day, date and month.(Image: Revolution)
The Patek Philippe Reference 5236P is the world’s first single aperture perpetual calendar with an inline display day, date and month.(Image: Revolution)

Patek had to rework the mechanism to achieve the in-line display in a wristwatch. While not quite on the same level of complexity as Philippe Dufour’s 1992 miniaturization of grand and petite sonnerie complications, this can be seen as a similar exercise in miniaturization and technical mastery. Patek reinvented the original, single date disc containing all 31 days by splitting it into two, as miniaturizing the single disc would have resulted in illegible numbers. This split-disc design, however, presented a new challenge: the tens and single digits require different actions at different times. For example, at the end of January, the single digit “1” remains, while the tens digit “3” needs to jump to “0.” This is a complex coordination absent from single-disc perpetual calendars or single-hand date mechanisms.

The caliber 31-260 PS QL's in-line display system relies on four disks (of which two are for the date) that are arranged on one level
The caliber 31-260 PS QL's in-line display system relies on four disks, including two dedicated to displaying the date in a larger format, all arranged on a single level

The quiet innovator: A. Lange & Söhne Lange 1 Perpetual Calendar

The second highlight, another standout launched at the same time, is the Lange 1 Perpetual Calendar. Renowned for its asymmetrical display, the Lange 1 (L1)  takes this concept further by seamlessly integrating the perpetual calendar indicators into its signature layout. Both the “salmon” and grey dial options offer perfect complements to the watch’s intricate, thoughtful, and understated design. In short, the L1 Perpetual Calendar is a high-end watch boasting an exclusive, yet subtle, design.

 

While lauded for its elegant appearance, the L1 Perpetual Calendar’s true brilliance lies in its movement. In a departure from traditional perpetual calendars that utilize a 48-tooth wheel, the Lange 1 employs a large peripheral ring surrounding the movement. This ring, coupled with a separate leap year mechanism, eliminates the need for the 48-tooth wheel, offering a space-saving and elegant alternative to the conventional mechanism present in almost all perpetual calendar watches. Oh, and every indicator jumps instantaneously – a bonus you won’t find in many other perpetual calendars.

The 2021 Lange 1 Perpetual Calendar (Image: Revolution)
The 2021 Lange 1 Perpetual Calendar (Image: Revolution)

The world’s thinnest: Bulgari Octo Finissimo Perpetual Calendar

The third highlight comes from the Italian jewelry brand Bulgari. As soon as you hear the name Bulgari, you probably already know that the watch is a record-setter in terms of thickness, or rather the lack thereof.

 

Indeed, the Octo Finissimo Perpetual Calendar, launched in 2021 – a great year for perpetual calendars – set the world record for thickness, with a movement that’s only 2.75 mm tall, bringing the entire watch to a mere 5.8 mm in height including the case. Notably, it surpassed the Audemars Piguet Royal Oak RD#2 Perpetual Calendar Ultra-Thin, which debuted in 2019 and held the world record for 2 years with a movement that’s 2.89 mm tall and a watch that’s 6.3 mm thick in its entirety. One of the reasons for this achievement is that Bulgari used a micro-rotor, while the AP RD#2 opted for a regular large rotor because the base movement is adapted from the Jaeger-LeCoultre cal. 920 – which performed admirably for a movement that’s several decades old.

For its first double retrograde perpetual calendar in the Octo Finissimo line, Bvlgari has chosen a design language that is original and fun.
For its first double retrograde perpetual calendar in the Octo Finissimo line, Bvlgari has chosen a design language that is original and fun.

That said, the Octo Finissimo Perpetual Calendar certainly offers more than just thinness. Its design is commendable as well. The calendar display follows the typical triple sub-dial format, but with a unique twist. Instead of the usual layout, it features an asymmetrical design with the date sub-dial being the largest at the top of the dial. Notably, it’s not just a normal date indicator but a retrograde date. Similarly, the leap year indicator at six o’clock also features a retrograde hand. With its ultra-thin profile, retrograde display, and tasteful layout, it’s hard to find a watch that can surpass its cool factors. 

The user-friendly masterpiece: Audemars Piguet Universelle RD#4 Ultra-Complication

The final two selections might appear slightly out of place on this list. While technically not perpetual calendar wristwatches, their inclusion is justified due to the presence of this complication. These timepieces delve into a realm of greater complexity, potentially warranting a separate category.

 

The fourth highlight is the Audemars Piguet Universelle RD#4 Ultra-Complication. This awe-inspiring watch boasts 23 functions and over 1,000 components within its movement, including a remarkable 17 safety mechanisms that safeguard against user error. This focus on user-friendliness elevates the RD#4 to one of the most approachable grand complications ever conceived.

Despite being amidst a plethora of features, the RD#4’s perpetual calendar deserves special mention for three reasons. Firstly, it is a remarkably compact module adapted from the RD#2, combining two levels of the mechanism into one for exceptional thinness. Secondly, it surpasses the capabilities of a typical perpetual calendar by navigating not just four-year cycles, but also the 100-year cycle. While most perpetual calendars only remain accurate until 2100 due to the exception rule for century years (non-leap years unless divisible by 400), the RD#4 extends this accuracy to 2400. However, it’s important to clarify that the RD#4 isn’t a “secular calendar” with a 400-year cycle perpetually encoded. It simply requires manual adjustments every 400 years. In comparison, standard perpetual calendars usually require adjustments every 100 years, and true secular calendars theoretically never need adjustments (assuming sufficient space on the year disc).

 

Finally, the RD#4’s perpetual calendar prioritizes practicality. The date, for instance, can be adjusted both forwards and backwards, eliminating the inconvenience of waiting for the watch to stop when accidentally setting the date too far ahead.

The legible perpetual calendar and the flying Tourbillon, with a classic three-arm carriage

The ultimate in accuracy: Furlan Marri Secular Perpetual Calendar

Last but not least, we present the Furlan Marri Secular Perpetual Calendar, a noteworthy addition to the world of watchmaking. While uncommon in the industry (can you name a few other watchmakers who have attempted this challenge?),Furlan Marri, a startup known for affordable reinterpretations of historical Patek Philippe designs, surprisingly debuted this timepiece at the Only Watch 2023 charity auction (which was scheduled for November 2023).

 

This watch is the result of a three-way collaboration. It brings together the expertise of Furlan Marri with the legendary Dominique Renaud, co-founder of complication specialist Renaud & Papi, and Julien Tixier, a rising independent watchmaker known for his prototyping skills.

Furlan Marri X Dominique Renaud X Julien Tixier – Secular Perpetual Calendar Pièce Unique For Only Watch 2023
Furlan Marri X Dominique Renaud X Julien Tixier – Secular Perpetual Calendar Pièce Unique For Only Watch 2023

The Furlan Marri Secular Perpetual Calendar represents a significant leap in watchmaking complexity. By replacing traditional recessed pushers with a large, user-friendly slider similar to a minute repeater, they prioritize functionality alongside innovation.

 

The watch’s true brilliance lies in its ability to incorporate the 400-year cycle with remarkable simplicity. Unlike typical perpetual calendars utilizing modules with around 200 components, this secular calendar module boasts a mere 25 parts, marking a major breakthrough in calendar complication design. This achievement is attributed to several ingenious technical choices.

 

Instead of the traditional grand lever, the Furlan Marri watch employs a space-saving peripheral rocker. Additionally, they have “reinvented” the 48-tooth wheel, replacing it with a simplified version that differentiates only between 30 and 31-day months. This new wheel, in conjunction with the peripheral rocker, ensures accurate date jumps regardless of the month’s length.

The clever and highly unusual mechanics of the secular perpetual calendar module

PERPETUAL CALENDAR

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