Of all the different kinds of watch complications, in terms of utility, Calendar displays are probably the most useful. The Date is the simplest complication on a watch with a Date Window aperture being the most common way to view this. Sometimes, the date can also be on a sub-dial. Sub-dials are attractive additions on the dial, adding an element of visual interest as well. Some watches have a date wheel where a centre hand with an arrow, points to the date along the chapter of the dial. This is called a ‘Bankers’ date.
From a simple second hand to the aesthetically pleasing moonphase function, complications run the gamut from useful tools to luxurious testaments to a watchmaker’s mastery. A Big Date allows a relatively larger view of the date and has the advantage of legibility compared to the traditional date window. The variation sometimes has two windows, the left one displaying 0-3, and the right window displaying 0-9. A day date tells the day of the week in addition to the date of the month.
Due to the varying length of the months, that is, 30 and 31 days, and then the leap year, watches with a calendar complication need constant adjustment to display the time correctly. These will reset after completing thirty-one 24-hour cycles, representing a full month, but, what about the time when there are 30 days? This is where the Annual Calendar comes in.

Slim d’Hermès Quantième Perpetuèl Platine featuring a perpetual calendar
An annual calendar complication is a complete calendar displaying the day, date and month with minimal adjustment. This complication automatically adjusts the date displayed on the timepiece based on 30 and 31 day months to ensure that the correct date is always displayed. It requires setting the date once per year, at the end of February, considering it does not take leap years into account.

Chopard L.U.C Perpetual Chrono – This calendar is recognisable by its large twin-aperture date display, complemented by indications of the day, the month and the cycle of standard and leap years.
Let’s face it, the watch industry is all about accuracy. To resolve this issue of the leap year, a Perpetual Calendar is a useful calendar complication that is easily the most complex type of calendar feature that exists on a watch displaying the date, day, month, and year. The striking feature here though, is that it also takes into account the leap year and will need correction only in the year 2100 when the leap year will be ignored.
This is the complexity that watchmakers have entered in the quest for accuracy. Perpetual calendars, understandably complex in themselves, are also a beauty to behold. Watchmakers ensure that aesthetics get prominence as well. Perpetual calendars, or rather any of the calendar complications have their own design features that add to the element of visual interest on the dial. Grand complications often incorporate calendar complications thanks to their usefulness and ability to work in tandem with and complement other complications.

The new Ref. 5320G Perpetual Calendar by Patek Philippe automatically indicates months with 28, 30, and 31 days and every four years also recognizes the 29th of February as a leap day.
With modern technology and smart watches, knowing the date is possible without any adjustment. Yet, the lure of calendar complications is time-tested and transcends all these technological introductions. After all, the marvel of mechanics is something that will never cease to fascinate! Let the calendar unfurl…