Haute Horlogerie

A Tribute to Eternity

Portugieser Eternal Calendar

An intricate mechanism, reaching further into the future than ever before – capturing the beauty of time and eternity.

A watch that precisely reproduces the Gregorian calendar’s complex rules, irregularities and exceptions – for thousands, even millions of years to come.

We are building on our comprehensive expertise in engineering mechanical calendars - and pushing the boundaries in watchmaking once again.

Portugieser Eternal Calendar watch dial unassembled on a black surface

The Portugieser Eternal Calendar

IWC Schaffhausen’s first secular perpetual calendar automatically takes into account the Gregorian calendar’s leap year exception rules by skipping three leap years over 400 years. It also features a moon phase display with an accuracy of 45 million years.

Front image showcasing the Eternal Calendar Watch with white dial and black strap on dark blue gradient background
Front image showcasing the Eternal Calendar Watch with white dial and black strap on dark blue gradient background
Illustration of the Eternal Calendar complication
The Portugieser Eternal Calendar dial separated from it's case
Front image showcasing the Eternal Calendar Watch with white dial and black strap on dark blue gradient background

Can precision be eternal? Our engineers set themselves the challenge of developing a moon phase display with unprecedented accuracy.

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Portugieser Eternal Calendar watch with open dial on white background

Take a look what’s underneath the dial


Double Moon™ display The Double Moon™ indication uses two superimposed discs to display the moon phase as seen from the Northern and Southern hemispheres on the dial.
Month cam As in a regular perpetual calendar, the mechanical calendar program is based on a disc containing a four-year cycle with 48 months, in which three common years followed by a leap year.
400-year wheel The 400-year wheel reflects the Gregorian calendar’s leap year exceptions. It completes just one revolution every four centuries and makes sure that the calendar skips three leap years over that period – an event that will take place in 2100 for the first time.
Moon Phase reduction gear On its orbit around the Earth, the moon does not follow a daily rhythm. One complete cycle from new moon to new moon does not last 30 days, but 29 days, 12 hours, 44 minutes and 2.88 seconds. To display the moon phase on the dial of a watch, the duration of one calendar months must be reduced to one lunar cycle. This is achieved by placing a reduction gear between the base movement and the moon phase disc.

Our recommendations

Available across a broad range of new models, IWC Schaffhausen’s signature colours Horizon Blue, Dune, Obsidian and Silver Moon reflect the eternal cycle of day and night.