A GIFT MADE FOR ETERNITY

No complication embodies IWC’s unique engineering approach quite like the perpetual calendar. Developed in the 1980s by Kurt Klaus and consisting of less than 100 ingeniously arranged parts, the calendar is distinguished by its high level of autonomy and user-friendliness. With the Portofino Perpetual Calendar, the iconic complication now returns to the Portofino collection in 18-carat 5N gold and stainless steel – marking the first Portofino Perpetual Calendar in stainless steel.

COMPACT AND VERSATILE

With a case diameter of just 40 millimeters, the Portofino Perpetual Calendar is currently the most compact perpetual calendar watch across IWC’s collections, ensuring perfect wearability for all wrist sizes. Integrated into a movement from the IWC-manufactured 82100 calibre family, the calendar displays the date, month, weekday and moon phase in three subdials at 3, 6, and 9 o’clock. A small indicator informs about whether the current year is a leap year. Another highlight is the perpetual moon phase display, which shows the moon against the backdrop of a star-studded sky.

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Portofino Perpetual Calendar Complication

THE IWC PERPETUAL CALENDAR

A FEAT OF ENGINEERING

A mechanical program for a wristwatch that replicates the Gregorian calendar with all its many irregularities: IWC’s former head watchmaker Kurt Klaus achieved this engineering feat in the 1980s with his legendary perpetual calendar. Designed as a separate module and driven by a single nightly switching impulse from the base movement, the calendar’s displays are perfectly synchronized with each other. As a result, they can be advanced simply via the crown, making it exceptionally easy to use.

SMART MECHANICAL PROGRAM

The heart of the mechanical program is the month cam, which provides the calendar module the information about the differing lengths of the months. It contains a complete four-year cycle with 48 recesses around its edge. One recess is different from all the others. When a dedicated lever falls into it, the calendar will know it’s a leap year and insert the 29th of February. This smart mechanical program will continue to run without manual intervention until 2100, when the leap year due is omitted due to an exception in the Gregorian calendar.

DOUBLE MOON PHASE DISPLAY

Selected perpetual calendar models in the Pilot’s Watches and Portugieser collections feature another innovation from IWC – the practical double moon phase display. It shows the current moon phase for the northern and southern hemispheres simultaneously, meaning you will see the correct moon phase no matter if you are in London or Johannesburg. Thanks to a special reductionist gear train, the display is so precise that it will only deviate from the actual orbit of Earth’s satellite by one day after 577.5 years.

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FOUR-DIGIT YEAR DISPLAY

Kurt Klaus’ perpetual calendar was also the first to feature a four-digit year display. Starting with the month wheel, an integrated transmission chain leads to a year wheel, a decade wheel, and, ultimately, a century slide. The latter is moved just 1.2 millimeters every 100 years. During the same period, a point on the balance rim theoretically travels a distance equal to 40 orbits of the Earth. Thanks to an additional century slide supplied within the case, the perpetual calendar will continue to function until 2499. The four-digit year display is featured on selected models in the Pilot’s Watches and Portugieser collections.

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