Perpetual Calendar Watches

The earliest perpetual calendar complication pocket watch dates back to 1762, when an English horologist, Thomas Mudge, invented it. In 1889, Patek Philippe patented the perpetual calendar in wristwatches. The first wristwatch with a perpetual calendar was built by Patek Philippe in 1925 and they built the first retrograde perpetual calendar in 1937. Patek was also the first to make the perpetual calendar chronograph in 1941. The first perpetual calendar pocket watch made by Thomas Mudge is now owned by Patek Philippe.

(First perpetual calendar watch made by Patek Philippe)

What is a perpetual calendar complication?

The perpetual calendar complication of a watch allows you to read the date of the year including the leap year. It works according to the Gregorian calendar for the date calculation. It takes account of all the short and long months of the year along with the 29 days of February in a leap. This exception makes the watch more complex than we think. With the perpetual calendar, the user doesn’t need to correct the date, at the time of the leap year, to 1st March. 

(The latest Patek Philippe perpetual calendar watches)

Gregorian calendar and leap year

Gregorian calendar was instituted by pope Gregory XIII in 1582 according to which the year is considered to be a leap year if the number of the year is divisible by 4 and if it is divisible by 100 then it should also be divisible by 400. Examples of leap years are 2016, 2000, 2020, and so on. The examples of the year, not a leap year are 2018, 1900, 1800, 1700, 2100, and so on.

(Lange and Söhne perpetual calendar 345.033)

Secular perpetual calendar

As 2100 is not a leap year in the Gregorian calendar, perpetual calendar watches need the user to adjust the date on 1 March 2100. Many perpetual calendars may need the year indicator to be replaced in the future when the centuries change that is 2100, 2200 and so on. This drawback of the perpetual calendar is taken care of by the secular perpetual calendar complication watches. Unlike the perpetual calendar, the secular perpetual calendar complication watches do not need manual adjustments ever, they take care of all aspects of the Gregorian calendar.

(The secular perpetual calendar of Patek Philippe)