In Depth: Patek Philippe References 3940 and 3970

In Depth: Patek Philippe References 3940 and 3970

| 08.18.23

To date on Transmissions, we’re referenced the Calatrava and some of Patek’s simpler models, but we haven’t yet explored the brand’s complicated offerings. Patek Philippe, of course, is one of the masters of high horology. (Haute horlogerie if you’re speaking with a French accent.) 

Today, we’re going to analyze two brilliant references from Patek’s history in depth, explain their significance and historical contexts, and help illustrate in general why the maison has risen to its level of fame and recognition within the industry. Though these are high-end pieces with correspondingly high-end price tags, understanding their mechanical complexities helps to put their values into context. 

The Watches

While there are dozens of notable references we could have chosen to highlight, in this case we’re focusing on the perpetual calendar Reference 3940 and perpetual calendar chronograph Reference 3970. Both watches were manufactured toward the latter portion of the 20th century and into the early 2000s. Produced alongside one another, they capture the brand’s styling and focus during the era, and also provide the foundation upon which modern Patek Philippe has continued to build.

A new Patek Philippe reference doesn’t arrive completely out of context; rather, the company has a vast library of past watches which they thoughtfully mine to inform the details of their new releases. This is part of the beauty of Patek Philippe as a brand — they respect their heritage implicitly, and make sure that whatever they produce is consistent with their legacy and with historical precedent. 

Many of the greatest companies in the watch industry have adopted a similar approach. Take Rolex, for example, who make only fine adjustments to their watches over time, maintaining the underlying DNA of a model line even while modernizing their timepieces. (Even a newer model family, such as the Sky Dweller, is informed by past Rolex model families.) This is one of the ingredients for a successful brand, and one that you will observe time and time again. 

In the case of Patek Philippe, take the in-line perpetual calendar Reference 5236P, introduced at Watches and Wonders in 2021. At first glance, it appeared quite modern. With a 41mm case, brand new movement, and complete in-line calendar display — a first for the brand in wristwatch form — it’s easy to view this watch as a completely fresh creation. Yet, looking further into the history of the model, and into Patek’s archive in general, yields a very different conclusion. 

5236P GRAND COMPLICATIONS - (Image by Patek Philippe)

The very first serially produced, automatic perpetual calendar wristwatch made by Patek, the Reference 3448, shares a large number of attributes. First, the aperture calendar display of the 3448 is featured on the 5236P, now updated to a complete in-line display that incorporates the date. The same underlying case geometry and lug definition of the 3448 is also reflected in the 5236P. But we can go back even further: Take a look at the pocket watch Reference P-1450. Once more, the same in-line display and the 6 o’clock moonphase display is reflected in the 5236P. 

Patek Philippe Perpetual Calendar Reference 3448 - (Image by Phillips)

This is much the same with the 3940 and 3970, which in the broader context of Patek’s history, are simultaneously “new” and “old.”


The 3940

Patek Philippe Perpetual Calendar Ref. 3940G -001 - IN THE SHOP

It’s important to understand the market dynamics surrounding the watch industry in 1985, the year of the 3940’s introduction. Watchmakers specializing in high horology had just been slammed by the Quartz Crisis, which began in the 1970s and continued well into the ‘80s. The Swiss watch industry lost over two thirds of its workforce seemingly overnight. As many maisons were forced to consider the future of their businesses, Patek Philippe released the 3940, which became both physically and symbolically important. 

Releasing an ultra-thin perpetual calendar wristwatch in the middle of the upheaval and uncertainty of the Quartz Crisis was a truly symbolic assertion from Patek Philippe that they would not bend or compromise in their commitment to producing fine mechanical timepieces as their core business. Despite the allure of inexpensive and highly accurate quartz timekeeping, Patek Philippe would continue to buckle down and create new high-horology creations. The 3940 housed the all-new Calibre 240Q, a movement whose base remains in watches the brand still makes to this day. This was an early in-house Patek movement — a further “middle finger” to the Quartz Crisis. Patek adapted, moving to prioritize hallmarks of quality (such as in-house movement production) in order to continue to distinguish themselves in an ever more competitive landscape. 

The 3970

Patek Philippe Perpetual Calendar Moonphase Chronograph Ref. 3970E - IN THE SHOP

The Reference 3970 was presented only a year after the 3940, in 1986. Successor to the Reference 2499 perpetual calendar chronograph, the 3970 was actually 1.5mm smaller in diameter than the 2499. While today we are certainly accustomed to larger watch sizes, the fact that Patek decreased the case diameter of the 3970 was (what the kids would call) a “flex.” Patek was indicating that it could produce a perpetual calendar chronograph that was highly wearable, and their ability to do so only increased with time. (With complications, smaller is always more difficult to achieve.) 

Patek Philippe Perpetual Calendar Moonphase Chronograph Ref. 3970E Case Back 

Beneath the caseback, the 3970 is equally noteworthy. The watch incorporates the Calibre CH 27-70 Q, the very first non-Valjoux based chronograph movement Patek had ever used. Instead, the CH 27-70 Q was built upon a Lemania base, the iconic Calibre 2310. (You may recognize the 2310’s architecture from the Omega caliber 321 outfitted in Ed White’s Speedmaster, for example.) The 2310 itself was introduced in the 1940s by Albert-Gustave Piguet, and quickly became one of the most important manually-wound chronograph calibers in history — if not the most important one. 

The Calibre 2310 was later included in the later Reference 5970, which is perceived by many as perhaps the greatest modern perpetual calendar chronograph. And if this isn’t enough, the same movement architecture is used in the Vacheron Constantin Cornes de Vache. You get the point — the movement is pretty darn cool! 

In some regards, the 3970 has suffered from being situated between the 2499 and the 5970. The 2499 is considered one of the greatest Pateks, and so is the 5970, albeit for different reasons. To some, the 3970 may stand out as a “misfit” of sorts — but these misfits are precisely where value is found. The 3970 is an incredible watch, and since it receives less press than the References 1518, 2499, and 5970, collectors can get involved in the magic of manually-wound perpetual calendar chronographs from the master of said complications at a fraction of the price. 

Aesthetics and Wearability 

The 3940

Patek Philippe Perpetual Calendar - IN THE SHOP

The Patek Philippe Reference 3940 could be described as the perfect everyday watch for the person who wears dressier pieces. It measures 36mm — a stellar size that’s optimally positioned between the small case sizes of vintage references and the imposing cases of many contemporary pieces. To add to the ease in day-to-day wearability, the watch is automatic, and exceptionally thin at just 8.5mm. Many brands struggle to produce time-only watches that are that thin and wearable, yet Patek has managed to integrate a full perpetual calendar into these dimensions. 

By this point, you will begin to understand the true brilliance of Patek Philippe. Earlier we mentioned that these watches were introduced in the midst of the Quartz Crisis, which further explains the importance of producing such a slim timepiece: Beyond merely competing with fellow companies to produce a thin mechanical watch with the 3940’s feature set, Patek also needed to offer something that would impress watch enthusiasts in a post-quartz world, where it was common to see a thinner timepiece. A tall order, indeed. 

To achieve a thin watch with an automatic winding movement, Patek employed the aforementioned Calibre 240Q. The 240Q utilizes a micro-rotor, a common go-to these for achieving a slim automatic watch; however, many don’t realize that adding an automatic winding system requires a rotor, automatic winding gear trains, and keyless winding works all to be present. This adds up to much higher number of components than a manually-wound watch would demand. Thus, most slim dress pieces from Patek — for example, the References 96, 3923, 5919, 3919, 6119 and others — are manually-wound. In fact, the Calatrava line is filled mostly with manually-wound movements (with several notable exceptions). 


Moving on to the layout and aesthetics of the 3940, we are met with a highly classical approach to perpetual calendar displays. In the past, Patek had used several types of layout for its QPs, from retrograde displays to the inline format we covered earlier. Perhaps the most recognizable modern layout with subsidiary dials is that introduced on the 3940, which also appears on the more modern Reference 5140 perpetual calendar. The case styling is also very characteristic of the era, with curved rather than sharp-edged lugs. (We see such a profile reflected in the Reference 3923 produced in the Calatrava collection from roughly the same era.)

In sum, the Reference 3940 was 1) released in the midst of the Quartz Crisis as a statement of Patek’s unwavering commitment to high horology; 2) is optimally sized for everyday wear given its balanced case diameter and its slim wrist presence; 3) employs the use of Calibre 240Q, which is thin at only 2.53mm tall, yet is automatically wound and produced fully in-house by Patek Philippe.

This is the kind of resumé that sets the stage for a perfect watch. The 3940 certainly receives attention within the connoisseur’s market of Patek collectors, but for some reason, never managed to achieve the degree of hype and fame that the Nautilus and other models have. It deserves that fame, but as is the case regarding the 3970, the lack of attention provides an opportunity for attentive collectors.

The 3970

Patek Philippe Perpetual Calendar Moonphase Chronograph Ref. 3970E - IN THE SHOP

Shifting gears to the 3970, we are met with a very similar picture, albeit with an entirely different story behind the caseback. (More on that later.) As a perpetual calendar chronograph, Patek Philippe has done a masterful job keeping the aesthetic DNA of the 3940 and 3970 consistent. At first glance, the two references actually look quite similar from the dial side. 

With respect to the 3970, the two hints that indicate an evolution from the 3940 are the apertures at 12 o’clock that display the day and month, as well as the chronograph hand and pushers. Patek needed to shift some of the calendar indications to 12 o’clock in order to accommodate the chronograph registers, while the 3940, which has no chronograph, simply places those calendar functions in the subsidiary dials. One of the most beautiful details that both watches share is a concave bezel. (It's a subtle detail, but boy, is it pretty.) 

Patek Philippe has done a fine job of breeding continuity within their collections. Other than the necessary changes to accommodate differences in complication, the watches remain very similar. Once more, when talking about the key ingredients for brand success, this continuity helps make watches recognizable as belonging to a particular or marque. (The same is true with fine automobiles, wherein a Porsche 911 looks like a Porsche 911, a Jeep looks like a Jeep, and a Mustang looks like a Mustang…except for that ghastly Mach-E. What the hell is that?!


The 3970 is outfitted with a manually-wound movement, versus the automatic mechanism of the 3940. (Outfitting a perpetual calendar chronograph with an automatic calibre would obscure the beauty of a manually-wound chronograph movement, so it’s good for us watch lovers that they went the hand-wound route.) Looking at watches like the A. Lange & Söhne Datograph and the Patek Philippe Reference 5170, you will undoubtedly agree that a manually-wound chronograph movement is a sight to behold. While there is certainly a convenience factor associated with automatic movements, the 3970 begs for a manually-wound movement by virtue of its complications. 

To accommodate the winding of the 3970, it is no surprise to find that the reference is outfitted with a much bigger crown than that of the 3940. It would be quite uncomfortable to have to manually wind the 3970 each day with a small crown, so in this case, function necessitates the crown playing a larger part in the overall aesthetics of the piece. 


Another reason for the ‘sleeper’ status of the 3970 is its 36mm sizing. The successor Reference 5970 made a big jump to 40mm in diameter. While this was done to accommodate the preferences of a newer generation of enthusiasts, a thick, 36mm complicated piece is much more comfortable than a thick, complicated 40mm  watch — with certain exceptions, of course.

The 5970 has its own charm, to be sure, but it’s a different appeal. Depending on the size of your wrist you may gravitate one way or another. 

Two of the Greatest References?

Having reviewed these two references side by side, hopefully you’re able to acknowledge just how special Patek Philippe is as a manufacture. These watches are equally significant in both their mechanical achievements and their symbolic messages. Released in a period of tumult within the industry, 3940 and 3970 are, arguably, two perfect timepieces. 

These are high-end watches, to be sure, but in the horological sphere, it’s always exciting to seek out hidden value. A 3940 still costs much less than a basic Nautilus on the secondary market and a 3970 can be had for similar money to the going rate for a Nautilus Reference 5711. As more and more collectors learn about the incredible beauty and importance of the 3940 and 3970, we can only expect prices to rise. It won’t be a surprise to anyone on our team when a white gold 3940 surpasses the six-figure mark. 

While they aren’t as flashy as orange-strapped Aquanauts or as well known as the Nautilus, these watches deserve every bit as much focus. After all, grand complications are Patek Philippe’s bread and butter, where they leave the competition in the dust and rise to a level matched by few. We’ll cover more high horology makers going forward, but there is arguably no better place to start than with the king of high horology, Patek Philippe. 

Be sure not to miss our new video covering the Patek Philippe 3940 in a Deep Dive! Click here