Calendar watches were introduced first time in the 16th century but their display of the time, days, dates and months were not too accurate. Neither they could mark Feb 29th separately on their own or decide between the 30th and the 31st. Correcting the date at least five times a year is not what you buy the watch for.
The latest answer to this problem is the perpetual calendar…Really? Is it so? But a true perpetual – we think – doesn’t end in 2099 or 2100. That means: Your perpetual shall not be a perpetual to your great-grandchildren.

Most perpetuals are based on the Gregorian calendar. Earlier calendar timepieces used the Julian calendar; the conceptual upgrade (counting one year as 365.25 days) resulted in requiring correct the time once every 133.33 years.

seiko perpetual calendar watch complication is a part of the Kinetic watches; it’s a classic mechanical perpetual calendar (till Feb 28, 2100) that will keep working internally for up to 4 years (Auto-Relay technology) even at complete rest. When picked up, the date and time will upgrade itself. After all, it’s modern microelectronics finding way into the classical watch-making domain.

The Seiko perpetual calendar design incorporates 101 parts (form the mechanical gear trains) and an ultra-sonic motor (0.4 mm) considered the thinnest in the world. The motor provides the energy separately for driving the Perpetual Calendar mechanism. There’s also a photo sensor that comes into play; it spots certain marks on the gear (pattern recognition) and keeps track of the calendar’s accuracy. Or you may say - It is about letting time be on your side.