Hamilton Khaki

Article By: Logan Hannen

What is up, watchfam?! Today, we’re going to take a look at the difference between an annual and perpetual calendar, so let’s get right into it!

Now, for the record, these are easily my favorite kinds of complications. Sure, every haute horlogerie brand in the world does one, but can you blame them? It’s a super cool complication, and one that still manages to show off some serious technical skill. I’m hooked pretty much for that reason. So what does the complication accomplish? Let’s talk.

First, the obvious: they’re both calendar complications that display information about more than just the time and numerical date. In both cases, you see the day, date, month, and sometimes even the year and, more often than not, the moon phase. The moon phase has become linked, interestingly enough, with this complication, though some of the most interesting ones in history (see: the Rolex Sky Dweller) have not featured this level of display. So we know what makes them similar, but what sets the two apart?

There’s really one distinguishing feature that separates the two complications, and it may not seem like much up front, but trust me, it’s super vital. The annual calendar, unlike the perpetual, needs to be manually adjusted once per year, on the jump from February 28th to March 1st (and, on leap years as well). A perpetual calendar, by contrast, never has to be manually adjusted (unless the power reserve runs down, obviously). It may seem miniscule, but this to me is the major thing that stands out. Being able to differentiate between 30 and 31 days in a month is definitely fascinating, but knowing when it’s time to jump from 28 to 1, or when it’s a leap year, just blows my damn mind.

There are some true beauties in this field, of course, including my personal grail, the Patek 5970, pictured above. Another Patek Calendar, the 5208T, is one that Christian has some pretty strong opinions on. Whichever way you decide to go in this complication, just be sure that you choose one that you really love, and one that will always help you to keep it classy, watchfam.