IWC Portugieser Eternal Calendar:
the charm of the eternal

IWC launches its first perpetual secular calendar: the Portugieser Eternal Calendar takes into account the complex exception rules of the Gregorian calendar for leap years.

IWC Portugieser Eternal Calendar

What IWC has a long and great experience in perpetual calendars is a fact. In the mid-1980s, Kurt Klaus, first a watchmaker and later head of movement design of the brand, decided to translate the numerous irregularities of the Gregorian calendar into a mechanical programme for a wristwatchwhich allowed all indications to be advanced synchronously and correctly with a single click of the mechanism. And for the first time, it made it possible to make all adjustments quickly via the crown.

IWC Portugieser Eternal Calendar

Almost forty years later, the House achieved a new technical feat and launched the Portugieser Eternal Calendar, its first secular perpetual calendar. In addition to recognising the different length of the months and adding a leap day every four years, the Portugieser Eternal Calendar takes into account the complex exception rules of the Gregorian calendar for leap years.

IWC Portugieser Eternal CalendarPortugieser Eternal Calendar: a technical challenge

IWC's 400th anniversary gear skips three leap years in four centuries.

A traditional perpetual calendar, usually designed for a four-year cycle, provides for a leap year after three common years. However, To maintain synchrony with the actual calendar year, secular years must be divisible by 400 to be considered leap years. This means, for example, that the years 2100, 2200 and 2300 will not be leap years despite the conventional cycle. Therefore, a perpetual calendar needs periodic corrections to accommodate these variations, requiring three corrections every 400 years.

IWC Portugieser Eternal Calendar

IWC's Portugieser Eternal Calendar, on the other hand, is capable of correctly calculating leap years up to at least 3999 (It has not yet been officially decided whether the year 4000 will be a leap year or not). An innovative gear, designed for a 400-year cycle, ensures that the calendar automatically skips three leap years within four centuries. This will happen for the first time in 2100. Apart from this additional mechanism, the Portugieser Eternal Calendar is based on the same modular and synchronised design as the existing perpetual calendar. All indications can be adjusted via the crown.

IWC Portugieser Eternal Calendar

Platinum for the Portugieser Eternal Calendar from IWC

A secular calendar with moon phases with a calculated accuracy of 45 million years.

But this is not the only technical feat of the Portugieser Eternal Calendar, which is also equipped with an extremely accurate moon phase display, deviating from the moon's orbit by only one day after 45 million years. It is driven by the automatic 52640 calibre, with a 7-day power reserve. For this model, IWC has made a platinum case and a distinctive white lacquered glass dial, the result of a very complex manufacturing process. It comes with a black alligator leather strap made by Santoni.

Price175,000 euro.

IWC Portugieser Eternal Calendar