Collecting the Patek Philippe Perpetual Calendar 3940

When it was clear that the then-new quartz technology would forever change the Swiss watch landscape in the 1970s and 1980s, different watch houses undertook different strategies to navigate the turbulent waters. Some embraced the quartz revolution by offering their best-selling watch models with quartz movements, some switched their entire catalogs to quartz timepieces, and some — such as, Patek Philippe — continued to emphasize the beauty and engineering excellence of traditional mechanical movements.

Of course, Patek did make quartz watches during that era (and continues to produce a few today); however, the company never abandoned mechanical movements and continued to work tirelessly in that department. This brings us to the famous Patek Philippe Perpetual Calendar 3940, which was a grand complication reference powered by a new automatic movement developed amid the quartz crisis and introduced in 1985.

Although the now-discontinued Patek Philippe 3940 was quite undervalued in the collector’s market, it has been increasing in value in recent years, thanks to more collectors and enthusiasts paying attention to this reference. As such, we’ve compiled a guide to collecting the Patek Philippe Perpetual Calendar 3940 that covers the history and evolution of the watch over four distinct series.

Caliber 240 was released in 1977 as a remarkable feat of micro-engineering. Although it was self-winding, Caliber 240 was as thin as a manual-winding movement, measuring a mere 2.53mm in height. Patek Philippe was able to achieve this thanks to a clever structure comprising of a very small, off-center winding rotor that was completely recessed in the plate plane. To make up for the rotor’s diminutive size, the rotor was fashioned in 22K gold to increase its mass, which in turn increased its winding power.

Furthermore, other technical touches were necessary to improve overall efficiencies, such as unidirectional winding for friction reduction, a new and improved wheel train to boost power reserve and accuracy, and a drop in frequency (to 3 Hz or 21,600 beats per hour) to reduce energy consumption. Remarkably, Caliber 240 (and multiple variations that use Caliber 240 as a base) is still at the heart of many current-production Patek Philippe watches.

Less than a decade after the launch of Caliber 240, Patek Philippe unveiled the Caliber 240 Q. The “Q” in the movement name stands for “Quantieme Perpetual” or “Perpetual Calendar” in French. So to develop the 240 Q, Patek took the already existing ultra-thin Caliber 240 self-winding movement and worked on the seemingly impossible task of adding a perpetual calendar module. The result was the ultra-thin perpetual calendar self-winding Caliber 240 Q movement, which measures a slim 3.75mm in height.

Caliber 240 Q made its debut in the Patek Philippe ref. 3940 Perpetual Calendar in 1985.

Patek Philippe 3940 - Caseback revealing caliber 240 Q

The Design of the Patek Philippe Perpetual Calendar 3940

Along with the new movement, Ref. 3940 also offered a new size and face for perpetual Calendar watches at Patek. For instance, the size was reduced to 36 mm and the pair of windows that displayed the day and month on preceding references was dropped in favor of subdial indicators.

Although a perpetual calendar is a complicated watch, the Patek ref. 3940 is easy to read thanks to its neat and legible dial. At three o’clock, there’s a subdial with the month and leap year indicators. At six o’clock, there are the date and moon phase displays. At nine o’clock, there are the day of the week and 24-hour (day/night) indicators. Finally, at the center is the duo of Dauphine hands for the hours and minutes.

Patek Philippe manufactured the Ref. 3940 from 1985 until 2007. As expected, several variations of the 3940 were made throughout its more than two-decade production run. In fact, there are three distinct series of the Patek Philippe Perpetual Calendar 3940 that we’ll cover in detail further below. However, there is the fundamental design blueprint of the ref. 3940 which remains constant throughout all variations and series.

36mm case in precious metal
Ref. 3940P – Platinum
Ref. 3940J – Yellow gold
Ref. 3940G – White gold
Ref. 3940R – Rose gold (starting with the Second Series)

Perpetual calendar function with indications for leap year cycle, month, date, day, moon phase, and day/night indicators. Central hours and minutes hands.
Dial with three subdials at 3, 6, and 9 o’clock
Sapphire crystal above the dial
Caliber 240 Q automatic movement with approximately 45 hours of power reserve

Enthusiasts and Patek Philippe scholars generally divide the manufacturing run of Reference 3940 into three distinct series, each defined by a set of signature design variations:

Patek Philippe Ref. 3940 Series 1 – 1985 to 1987
Patek Philippe Ref. 3940 Series 2 – 1987 to 1995
Patek Philippe Ref. 3940 Series 3 – 1995 to 2007

While exact production numbers are not known, it is estimated that Patek Philippe made between 7,000 and 8,000 examples of the Ref. 3940.

Patek Philippe Ref. 3940 Series 1

The Patek Philippe 3940 watches produced from 1985 until 1987 are defined as Series 1 and are characterized by the following design traits:

Stepped subdials at 3 and 9 o’clock with month and day printed on the main dial while leap year and day/night indicator are printed in the recesses
No crosshairs on leap year indicator
There is a grave accent in “GENÈVE” below PATEK PHILIPPE on the dial
The Sigma “σ SWISS σ” label is printed below the dotted minute marker
Hallmarks (750 and Helvetia symbol for gold examples; 950 for platinum examples) are engraved on the left side of the case
Solid caseback

It is estimated that only about 700 examples of the First Series Patek ref. 3940 were produced.

Beyer Dial Variants

Philippe Stern, the President of Patek Philippe at the time, and Teddy Beyer of Chronometrie Beyer were great friends. As such, to celebrate the 225th anniversary of Chronometrie Beyer, the very first 25 examples of the Patek Philippe Perpetual Calendar ref. 3940 were stamped with BEYER, numbered, and sold exclusively at the famed retailer in Zurich, Switzerland. The first 15 included a German calendar while the remaining 10 included an English calendar. As expected, Teddy Beyer wore No. 1, and the watch is now displayed at the Clock and Watch Museum Beyer Zurich below the store. No. 2 is currently housed at the Patek Philippe museum in Geneva, but it once belonged to a renowned collector.

Patek Philippe 3940J - Series 1 | Twain Time

Patek Philippe Ref. 3940 - Series 1

Patek Philippe Ref. 3940 Series 2

The Patek Philippe 3940 watches produced from 1987 until 1995 belong to Series 2, and are characterized by the following design traits:

No accent in “GENEVE”
Larger PATEK PHILIPPE name on the dial
The Sigma “σ SWISS σ” label is printed below the dotted minute marker
Solid caseback or special-request display caseback. Towards the latter part of the Second Series production, Patek began offering the Ref. 3940 with a display caseback along with an additional solid caseback in the box. The platinum versions are the exception as those were only offered with solid casebacks.
Beveled sunken subdials at 3 and 9 o’clock. Month and day are printed on the beveled slope while leap year and day/night indicators are printed in the recesses
No crosshairs on leap year indicator on early examples; crosshairs on examples produced from 1989 onwards
Hallmarks (750 and Helvetia symbol for gold examples; 950 for platinum examples) are engraved on the left side of the case. Late 2nd Series Patek Philippe 3940 examples have hallmarks on the case side and underneath the bottom pair of lugs

It is estimated that about 3,500 Second Series Patek ref. 3940 watches were produced.

Patek Philippe 3940R - Series 2

Patek Philippe Ref. 3940 Series 3

The Patek Philippe 3940 watches produced from 1995 until the end of production in 2007 belong to Series 3. These have the following design characteristics.

No accent in “GENEVE”
Larger PATEK PHILIPPE name on the dial
The Sigma “σ SWISS σ” label is printed in line with the dotted minute marker
All models (except for the platinum one) came with display casebacks along with the extra solid caseback in the box
The movement is now marked as Caliber 240/114. The rotor inside the movement is marked with a Calatrava cross
Beveled sunken subdials at 3 and 9 o’clock. Month and day are printed on the beveled slope while leap year and day/night indicators are printed in the recesses. Subdials began adopting a more modern sans serif font
Crosshairs on leap year indicator
From 1997 onwards, all models fitted with leather straps included a deployant buckle instead of a pin buckle
By 2004, the undersides of all the lugs include hallmarks and they no longer appear on the case sides

It is estimated that Patek produced about 2,200 examples of the Third Series Patek ref. 3940. The Perpetual Calendar Ref. 3940 was replaced by the Perpetual Calendar Ref. 5140 in 2007.

Patek Philippe 3940R - Series 3

Important Patek Philippe Ref. 3940 Variants

Patek Philippe Ref. 3940 Limited Edition 2015

While the regular production Ref. 3940 came to an end in 2007, Patek Philippe released a limited edition in 2015 during its Grand Exhibit at London’s Saatchi Gallery. This so-called “Saatchi” edition paired new old stock ref. 3940 cases with ref. 5140 style dials in various shades. Though Patek made yellow gold and platinum versions of the 2015 ref. 3940, the white gold variant with a salmon dial is regarded as the most desirable of the batch.

Patek Philippe Ref. 3940 with Bracelets

Although the vast majority of Patek Philippe Perpetual Calendar ref. 3940 came fitted with leather straps, there are some examples in the secondary market that were fitted with gold bracelets such as beads-of-rice bracelets and flat-link bracelets.

Double Signed Patek Philippe Ref. 3940

Aside from the Beyer examples we already outlined, there are also Ref. 3940 variants stamped with retailers Gübelin and Tiffany & Co. As expected, these double-stamped Patek 3940 examples are highly collectible thanks to their rarity.

Patek Philippe Ref. 3940 with Roman Numeral Dials

Starting with the Second Series, Patek Philippe furnished a few Ref. 3940 watches with white porcelain dials featuring painted black Roman numerals and a rail-style minute track. The Patek Philippe ref. 3940J-025 in yellow gold is an example of the Roman numeral dial variant.

Patek Philippe Perpetual Calendar Ref. 3940J-25

Language Variations of the Patek Philippe Ref. 3940

Most Patek Philippe ref. 3940 watches will have English names for the months and days on the dial. However, Patek did also produce German dials (as on the Beyer variants for example) as well as French and Italian ones.

Patek Philippe ref. 3941

The Ref. 3941 was a short-lived reference that was identical to the 3940 First Series except it featured a display caseback rather than a solid one. Patek eventually phased out the reference when it began offering the display caseback option from the 3940 Second Series onwards.

The Value and Collectability of the Patek Philippe Perpetual Calendar 3940

The Patek Philippe 3940 was produced far longer and in far greater quantities than its predecessor, the ref. 3450. That may help to explain why, for a long time, the reference was often found at less than half the retail value in the secondary market. For context, the last published retail price for a yellow gold Patek Philippe 3940 was 61,000 Swiss Francs. In short, the Perpetual Calendar ref. 3940 was quite undervalued in the collector’s market, despite its significance to Patek Philippe’s history.

Yet, like so many often-overlooked creations by renowned brands such as Patek, collectors are waking up to the ref. 3940 and this newfound attention has naturally driven up the price of the reference. Today, the starting prices for pre-owned Patek Philippe ref. 3940 watches in yellow gold are slightly more than $50,000 and can be much higher for other metals or sought-after variants.

Generally speaking (and this applies to almost all Patek references), white metal variants of the 3940 will command higher prices than yellow gold versions simply because fewer of them were made. Furthermore, First Series 3940 are typically more valuable than Second and Third Series examples, while those ultra-rare variants such as double stamped retailer ones are particularly coveted by collectors.

Twain Time is proud to offer a selection of pre-owned Patek Philippe Grand Complication Perpetual Calendar ref. 3940 watches, each dutifully inspected by our in-house master watchmaker to ensure excellent condition and performance.

Patek Philippe Perpetual Calendar 3940R

How to Use the Patek Philippe Grand Complication Perpetual Calendar 3940

The Patek Philippe Grand Complication Perpetual Calendar reference 3940 runs on the self-winding Caliber 240 Q and includes the following functions:

Central hour and minute hands
3 o’clock Subdial: Month and Leap Year indicators
6 o’clock Subdial: Date and Moon phase indicator
9 o’clock Subdial: Day and 24-Hour indicator

Thanks to a 48-month (four years) cam, the perpetual calendar complication automatically displays the correct date, accounting for the specific days in a month, including leap years. As long as it keeps running, the Patek Philippe ref. 3940 does not require correcting until the year 2100, when the 29th of February will be skipped.

To Wind and Adjust the Time of the Patek Philippe ref. 3940

To manually wind the watch, turn the winding crown clockwise whilst it is pushed into the case
To set the time, pull the winding crown and turn it either clockwise (to move the hands forward) or anticlockwise (to move the hands backward)
Note the A.M. hours or P.M. hours according to the 24-hour indicator
Always push the crown back into the case before wearing it

How to Set the Calendar Functions of the Patek Philippe ref. 3940

To set the day of the week, push the corrector button on the case at the 9:00 position
To set the date, push the corrector button on the case at the 11:30 position
To set the month, push the corrector button on the case at the 12:30 position
To set the moon phase, push the corrector button on the case at the 6:00 position

Precautions When Setting a Patek Philippe ref. 3940

Avoid pulling out the crown in humid environments as this could allow moisture to get into the movement or watch
Do not set the watch while it is on the wrist; it could add unnecessary pressure to the winding crown
Use the appropriate correction stylus to press the push-piece to avoid damaging the case
Do not adjust any functions of the watch during the hours of 9 P.M. and 3 A.M. It’s safest to adjust the time to 6 o’clock prior to adjusting any calendar functions

Celine Simon | Posted on October 08 2022

Collecting the Patek Philippe Perpetual Calendar 3940

Table of Contents:

Caliber 240 Q