EP 1: Perpetual and Annual Calendar Watches

Watch Calendar and their history!

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Watch Calendar

Have you ever had a timepiece that tells you more than just the day’s time? Have you noticed some tiny dials with arrows indicating the day or date of the month? There are a lot of variations on how a watch brand might showcase it. 

Some use dials and an extra hand to indicate the date others might use a tiny aperture window with a rotating disk underneath with numbers from one to thirty-one. Some watches have a larger aperture window with two rotating disks underneath. These all are calendars and in the watch world, there are mainly two types of calendars, the Annual Calendar and the Perpetual Calendar.

Brief History of the Modern Calendar

Before we get into the nitty gritty of month, day, and dates, let’s take a look at the brief history of the calendar, and how it works!

The calendar has been an integral part of various civilizations since the dawn of time, as it's used to keep track of time. In ancient times calendars primarily served cultural and practical purposes often connected to astronomy and agriculture activities.

In the beginning, there were traces of civilizations like Sumerians, Egyptians, and Mayans used calendars that were lunar-based because moon phases were easier to read and hence divided the year into 12 months based on the lunar cycle. 

With their deep understanding of astronomy, the Egyptians were the first to develop a solar calendar, based on the Earth’s orbit around the Sun, which takes around 365 days, consisting of 12 months of 30 days each, with extra 5 days added at the end of the year. 

The Lunisolar calendar is the one that takes count of both the solar calendar and the lunar calendar, in which the months are lunar but the years are solar. The dates of the lunisolar calendar indicate both the Moon phases and the position of the Sun on the Earth.  The one we use today originated from the Roman calendar, it was based on a lunar calendar, and the year began in March and consisted of 355 days. 

Julius Caesar reformed the Roman calendar by adopting the solar year in 46 BC, he added three intercalary months and rearranged the length of the months. Based on his calendar, now there were 365.25 days in a year. A four-year leap year cycle was added to adjust the .25 of the day, hence changing the beginning of the year from March to January, it was called the Julian calendar. 

The calendar we follow today is the Gregorian calendar which is based on the solar cycle. Pope Gregory XIII took it upon himself to create the calendar we follow today and made adjustments to address the inaccuracies in the Julian calendar which made everything simpler but had a tiny flaw. 

The solar year is 11 minutes shorter than the Julian calendar and every 128 years the Julian year falls one day behind the solar year. Pope Gregory XIII shortened the calendar by almost 12 minutes and The Gregorian calendar leap year happens every four years except the years divisible by 100 but not 400. This made it so accurate that it will only fall behind one day every few thousand years.

Annual Calendar Watches 

An annual calendar mechanical watch complication will show you the day, date, and month on the face of the watch. But as the name suggests it’s an annual calendar so the watch would have to be reset once every year.

An annual calendar watch must be adjusted on March 1st because February is the shortest month of the year and the one where an extra day of the leap year is added.

Because a mechanical annual calendar watch cannot differentiate whether it is a year or not. 

An annual calendar can automatically adjust between a 30-day or 31-day month. It is also capable of recognizing that some consequent months have both 31-day months for example July and August, but also shifts the day indicator to full days and the end of the month.

The first annual calendar was introduced way after the perpetual calendar in 1996 by Patek Philippe. The Caliber 315 QA mechanism Ref. 5035 in yellow gold, annual calendar complication was simpler than a perceptual calendar. It was more accessible and user-friendly with almost all of the functionality of a perpetual calendar watch. These timepieces are famous among watch collectors and enthusiasts, despite being an annual calendar their impact on the watch world is truly perpetual.

Famous Annual Calendar Watches 

Perpetual Calendar Watches  

As the name suggests perpetual calendar complication has been truly perpetual in the watch community, it stands as one of the most enduring and renowned innovations, holding equal importance in timekeeping.

In 1762, an English watchmaker Thomas Madge graced us with a complication eternal to the watchmaking community, the perpetual calendar was first introduced as a pocket watch, though this invention did not see the light of the day for nearly a century when Patek made their movement and it was until 1925 when Patek Phillipe showcased the world’s first perpetual calendar wristwatch, The Patek 97975. 

A watch with a much more sophisticated and intricate mechanism which is generally more expensive is a perpetual calendar, Just like an annual calendar, it shows the day, date, and month of the year. It's a highly complicated complication that keeps track of the date of the month correctly year after year including leap years

Some months have 31 days, and some have 30 days. And then we have February which has either 28 or 29 days depending on whether it’s a leap year. A perpetual calendar will keep track of the date irrespective of an annual calendar where you either have only 30 days or 31 days.

Some common perpetual calendar watches are the digital Casio and G-Shocks these watches are fairly simple to manufacture and program into a chip and are inexpensive compared to mechanical complications which are in a whole different league when it comes to the mechanism, complication, and the price point. 

A perpetual calendar is complex and creating this movement in a mechanical watch is highly intricate, often necessitating hundreds of mechanical parts such as wheels, gears, and levers. Contrary to what the name implies a mechanical perpetual calendar will also require a manual adjustment in the year 2100, as it’s not a leap year. 

Famous Perpetual Calendar Watches

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