The Perpetual Calendar, a real challenge.

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The Swiss Watch-making industry has an incredible concentration of creative minds. From the hands of a watch-maker, you might see true wonders bursting into the world. And probably the highest wonder of all is the Perpetual calendar complication.

Thank you Romans

Displaying the date for a watch does not seem a big deal. But displaying it correctly represents a true challenge. Why? Well because some month have 30 days and others 31. February is a mess. In some years, called leap or bissextile years, it has 29 days and in others common years only 28. Why such a sophisticated organization? Most are purely political and others religious.
We should be “thankful”to the Ancient Romans for our modern calendar. At that time, the annual calendar had only 10 month equally with 30 days (precisely 29.530589 days in average) as it was following a Lunar calendar. We can see the Roman influence as some month are named in honor of Ancient Roman gods like Janus (January) or Mars (March).
Of course it would have been too easy for our Watch-maker to present a calendar as it would simply be a 30 times revolution of 24h. But thanks to politics and some good religious strategy, things got complicated.
Under the reign of Caesar Augustus, the solar calendar became the reference.

Roman Solar calendar

So 2 more extra month needed to be added to fulfill the 12 periods of solar revolution. In order to honor Caesar dynasty they added Augustus (August) and Julius (July). October was renamed in honor of Caesar Octavius. Naturally being the months of Emperors they had to have more days, so 31 days were a more appropriate number.

Caesar Augustus

And here our Watch-maker would start scratching his head. Things became worth when Pope Gregory decided to add an extra day to February every 4 years. We call it Bissextile or leap year. This decision would fix two main problems. The first was a astronomic reason: our 365 days calendar is actually 6 hours shorter than the true solar revolution. So by adding an extra say every 4 years solves this issue.

Pope Gregory

Another point to understand is that Pope Gregory was definitely a true defender of Christianism supremacy among pagans. As the Spring Equinox was an important ancient pagan feast, Pope Gregory wished to stick Easter as close as possible of this each year. So Christianity would prevail on paganism. That’s why we have such complex annual calendar and that your simple-based watch needs some manual adjustments from time to time.

Perpetual Calendar complication to the rescue!

What we know for sure is that measuring time, meaning precisely measuring time, is an obsession for men since the Babylonians. Decade after decade master watch-makers tried to be as accurate as possible. It was all about technicity, creativity and ingenuity. So when the first watch displaying the date on its dial was presented, it was already an amazing revolution. Every day at midnight, the watch would change the day/date displayed and the watch owner would need to manual set the date every end of the Month that has not 31 days. Rolex launched its first Day-Date watch in 1956 and several brands followed. The true revolution came with the Breguet n.4244 and for the very first time a Perpetual calendar not manufactured for a pocket watch. Produced in 1929 and sold only in 1934, this amazing watch represented a big revolution in watch-making.

Breguet 4244
Each Perpetual Calendar might contain different components or specifications but in general they all have a disk or wheel that will take 4 years to accomplish a full turn and this will mark the bissextile years. Most of the timepieces with such mechanism will give the day and date precisely until 2100. And in that year they all shall get a manual manipulation as that year is not a bissextile one. Only IWC has a “Grande Complication” that will allow the mechanism to deliver a exact date until 2400. And since then, the Perpetual calendar or Quantième Perpetuel represents one of the biggest achievements for a Brand.
Here are some of recent great timepieces with such complication.

Patek Philippe Grande Complication

Patek Philippe Grande Complication

IWC Portuguese Perpetual Calendar

IWC Portuguese Perpetual Calendar

Jaeger-LeCoultre Master Grand Reveil

Jaeger-LeCoultre Master Grand Reveil

Of course Prices are very high as the manufacturing of such masterpieces are also quite complex. So now you know what is a Perpetual Calendar.

Info sourced at, wikipedia and the following websites: IWC, Patek Philippe, Rolex, Audemars Piguet, Jaeger-LeCoultre, Federation Suisse d’Horlogerie, All content is copyrighted with no reproduction rights available.

Sebastien Eich

Sebastien Eich is passionate about Swiss watch-making and throughout the years he gathered a tremendous amount of knowledge about the beautiful art of creating a watch. Based in Switzerland, the mother land of watch-making, he has exclusive access to Brands and events. He shares all of it here for the great pleasure of sharing.