The Annual Calendar was designed by Patek Philippe as a simple version of the perpetual calendar. However, unlike the perpetual calendar, which automatically displays the correct time and date, the annual calendar needs to be readjusted once a year to accommodate the particular length of February.
Perpetual calendar replica watches automatically adjust to display the (almost) permanent date correctly, as this complication also takes into account leap years. However, in 2100, scheduled leap years will be skipped, so even the perpetual calendar will need to be manually adjusted – but none of us will be alive by then, so that’s not our concern! 
The dial of the 5035 Annual Calendar contains a wealth of information. At the center are the luminous leaf-shaped hands that sweep around the dial and point to the luminous Roman numerals. Then there are three subdials showing the month, 24-hour time, and date. Finally, there is a discreet date window at 6 o’clock. As with most modern Patek Philippe watches, the back is fitted with a sapphire crystal, allowing a clear view of the movement inside. In this case, the engine is the automatic caliber 315/198, which provides the user with a power reserve of approximately 40-45 hours.
As with most modern Patek Philippe watches, the back is equipped with a sapphire crystal, allowing a clear view of the movement inside. In this case, the engine is the automatic caliber 315/198, which provides the user with a power reserve of about 40-45 hours. In 2005, Patek Philippe replaced Ref. 5035 with the Annual Calendar ref. 5146. With the introduction of the second generation of the Annual Calendar, Patek Philippe brought a large number of changes.
To begin with, the case size was expanded to 39 mm – more in line with the market demand for larger men’s watches. However, the 5146 is also available in yellow gold, white gold, rose gold, and platinum. However, in addition to the leather strap option, Patek Philippe replica watches now offer all three yellow gold versions with full gold links.
Apart from the design changes, the Annual Calendar ref. 5146 also offers additional displays on the dial. In addition to the time, date, day, and month, Patek Philippe’s annual calendar models now feature a moon phase display and a power reserve indicator. The luminescent Roman numerals that filled the old model have been replaced by a mixture of Arabic and faceted indices, along with small luminescent episodes on the outside of the railroad minute track. In contrast, the platinum version has only faceted indices and no hour-marked numerals at all.
As far as the movement is concerned, the early annual calendar ref. 5146 used the caliber 315/299, which operated at 21,600 vibrations per hour. 5146 watches are also equipped with a sapphire caseback, and those with the latest movements provide the user with a power reserve of approximately 45 hours. If you have an annual calendar watch, be it a Patek Philippe Annual Calendar, Rolex Sky-Dweller, or any other model, don’t forget to adjust it on March 1.