Watches are beautiful pieces and there is a fine piece of work within them. Besides keeping the time perfectly, they also seem to keep the date without any problem. This may raise the question for some of you watch owners, how do watches actually know the day?

Analog watches cannot know or sense the exact date. Most watches have a date wheel that runs every 24 hours and runs from 1-31 days. Therefore, the date is expected to be manually corrected 5 times a year (during 30-day months). Perpetual calendars are set during manufacture so they always know the exact date.

So, watches are actually not so perfect that they know exactly what date it is on their own, which actually makes sense. We explain why this is not possible and how it might still be possible.

Why normal watches can’t know the date automatically:

If watches can keep track of the minutes, hours, and seconds, why can’t they automatically keep track of the month?

Keeping track of the day and month would be extremely difficult on analog watches. You can probably imagine this, because then a setting would have to be made in the timepiece so that it changes every month on a different day of the month. Analog watches like mechanical watches and Quartz watches with a calendar disc keep the date using a reduction gear train.

This means that watches are set to, as it were, just spin around. Therefore, the watch operates according to a standard procedure, and cannot change every first of the month on its own. This process goes like this:

  1. The hour wheel turns, once every 12 hours.
  2. Transitions to intermediate date wheel.
  3. Drive wheel.
  4. Date disc to make it visible on your watch.

This process can simply not be changed and this continues one after the other, so that the watch cannot suddenly change automatically on other days.

Analog watches

Is it possible to make a watch know the exact day?

We’ve now talked about analog watches, how they keep the date and why they can’t keep the date automatically. However some watches have a feature called an “annual calendar” or “perpetual calendar.” This is a special feature in a watch, usually the more expensive watches, which we would like to tell more about since it offers possibilities regarding the date on your watch.

Annual calendar:

We start with an annual calendar, this is the simpler one of the 2. This calendar has the ability to track the 30 and 31 days in a month without any effort from the owner. That is not entirely true, by the way, because the owner has to adjust the date every year on March 1, this has to do with the fact that the annual calendar cannot process shorter days than 30 days.

A perpetual calendar is a little more complicated. A perpetual calendar is a timepiece, usually mechanical, which in itself keeps and records calendar information. As a result, it always displays the correct date.

Perpetual calendars:

The perpetual calendars are set up exactly in such a way that they are already in the correct date well into the distant future. This means that watch makers have already set the dates for the next tens / hundreds of years when making the watches. This way, it will keep track of all the months and special days and years. And there is no further action required.

The fact that this feature is put in a watch takes a lot of effort and more actions in making the watch. This may require 100 or more additional parts. Which also explains that these watches with these features are often a lot more expensive.

How do you set the date of your watch on 30-day months?

So let’s go back to normal people for a moment, with normal watches. Which do not have all the expensive extras on it. If you just have a normal watch, you can make sure that your watch is correct in terms of date every month.

As we have already mentioned, you will have to manually adjust your watch. Which you usually do 5 times a year. This has to do with the fact that in a year, there are 5 months with 30 days, on which you have to adjust your watch. Moving the date on your watch is pretty easy once you know how to do it. You do this by using the button on the right side of your watch, the crown.

Pull this button out of your watch and then turn it forward until your watch is on the correct date and time, then press the button again to confirm the settings.

Adjusting a watch date requires a few rules. Rule number one is to not change the date between 9 PM and 3 AM. You can look at this short video on how to set a watch, and what not to do:

Changing the date on your watch at the wrong time can have a negative effect on the health of your watch. So don’t make this mistake.

How do watches know Leap Year then?

A leap year is of course a completely different story, we actually learned all the ins and outs of changing the date from this article. We now know which watches can and cannot do this on their own. So how do watches know leap year?

Analog watches (mechanical and quartz) cannot automatically anticipate leap year. Perpetual calendars can, and are already set to indicate a leap year at the time of manufacture. This function is often considerably more expensive.

In a leap year, it therefore becomes a bit of a switch when you use an analog watch. It’s not a disaster in itself and it’s fine to do this a few times a year, you can put it in your agenda if you want.

In this article we learned a lot, in fact, everything you need to know about setting the date on your watch. We learned why not all watches can display the date automatically, how to fix this, and some additional details. Also, we learned how to adjust your watch, and what not to do while moving. We hope to have provided enough information about how to use a watch if you have to set the date again. If your’e interested take a look at some of the following posts:

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