A secular perpetual calendar, with a moon phase display accurate to 45 million years.

Watches and Wonders Geneva 2024: April 9th – April 15th, 2024.

IWC Schaffhausen has unveiled the Portugieser Eternal Calendar at Watches and Wonders Geneva 2024. This grand complication timepiece draws on IWC’s almost 40 years of expertise in perpetual calendar expertise. It belongs to IWC’s Portugieser family of timepieces.

The Eternal Calendar is IWC’s first secular perpetual calendar.

“In addition to recognising the different lengths of the months and adding a leap year every four years, the Portugieser Eternal Calendar also takes into account the Gregorian calendar’s complex leap-year exception rules.”  This is achieved by a “newly engineered 400-years gear”  that makes sure the calendar functions automatically skip three leap years over four centuries or 400 years, an occurrence that will first take place in the year 2100.

The Eternal Calendar’s highly precise moon phase display is another key feature. A newly developed reduction gear ensures that the Double Moon™ phase display deviates from the moon’s orbit by only one day after 45 million years.

Functions and Dial

The Eternal Calendar’s functions are:

– Hours and Minutes.

– Perpetual Double Moon™ phase display with 45 million years accuracy for both the northern and southern hemispheres displayed on the subdial at 12 o’clock.

– Date and 7-day power reserve displayed on the subdial at 3 o’clock.

– Day of the week and small hacking seconds displayed on the subdial at 9 o’clock.

– Months displayed on the subdial at 6 o’clock.

– Year displayed in 4-digits between 7 o’clock and 8 o’clock.

– 400-years gear that recognises irregular leap years over four centuries is located between 4 o’clock and 5 o’clock.

Its dial is crafted using glass and white lacquer in a complex process. The Arabic numerals and hands are rhodium plated. The Arabic numerals and minute scale “are printed on a white lacquered flange sitting between the glass dial and the front glass.”

Case and Strap

The Eternal Calendar’s case is crafted in platinum with both polished and brushed surfaces. It has a case diameter of 44.4 mm and a case height of 15 mm. On both the dial and caseback side, there is a sapphire box glass, with anti-reflective coating on both sides. It is water resistant up to 5 bar. The timepiece comes with a black alligator strap from Santoni of Italy with a platinum folding clasp.


The Eternal Calendar is powered by in-house mechanical self-winding calibre 52640, which features IWC’s Pellaton automatic winding system. It has 54 jewels, beats at a frequency of 28,800 vph or 4 Hz and has a power reserve of 7 days or 168 hours. It features movement finishing such as circular graining and Geneva stripes. Calibre 52640 is visible via a sapphire caseback.

Availability and Pricing

Name: Portugieser Eternal Calendar

Reference: IW505701

Price: Not available at time of authoring this article.


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