How Day Date Watches Work – Automatic Watches

The iconic watch that we wear regularly that tells us the day and date today has a long history to tell, if it can only talk.

It even has a name. It is called a day date watch. It is the simplest watch complication. It shows the day of the week plus the date.

The date operation should be adjusted manually at the end of months that only have 30 days and also on February because the mechanism of a day date watch is designed for 31 day months. This is to manually correct the date at the beginning of each month.

In the mechanical day date watch, if we could only watch through a transparent window at the back (yes a lot of watches do), we could see the hour wheel, and it controls the rotation of the hour and minute hands. It also mobilizes the date train.

A typical watch operates on a 12 hour dial, making the hour wheel rotate for once for every 12 hours. This rotation movement, in turn, moves the date disc driving wheel around too, at double the ratio. This explains the 24 hours of a day.

There is only one tooth for the date disc driving wheel, which makes it rotate exactly only once per day. This reflects in the changing of the day and date exactly once every day too.

But as explained above, since day date complications run on 31 day design, the watch owner is expected to manually change the date on the first day of the month following a month with less than 31 days. This occurs only 5 times every year.

The date window of the day date watch is usually found as an aperture or small opening at the 3 o’clock or 6 o’clock side of the watch facade. It usually has a magnifying glass over it which looks like a big drop of water. In watch parlance, it’s called a cyclops.

The day and date on the day date watch should change at exactly 12 midnight. If there’s an advancement or a delay in the day and date turnover, this means there is some disalignment in the moving parts and it needs to be serviced soon.


The luxurious image of the mechanical day date watch still lives on through the steady and prosperous existence of quality watch makers who have withstood the test of time and two World Wars. They are mostly European companies which have handed down their watchmaking artistry from generation to generation.

Mechanical watches have value. They appreciate in price just like real estate. But they need a lot of care and correct usage:

  • Store your watch properly. Don’t keep or expose your watch in conditions that have extreme heat or coldness. They cause damage to the watch movement and the gaskets. Sudden change of temperature can also make the parts expand and contract. You don’t want moisture to enter the dial and the moving parts to cause damage. Heat, for one, can make the lubricant dry out and create damaging friction on the gears. If extreme temperatures can’t be avoided, have your watch serviced immediately afterwards.
  • Don’t wind or set the time of your watch on your wrist. It may seem lazy, fast and convenient to do this, but it’s a precursor of some bad things to happen. The improper angle that you’re working on as you wind may cause stress on the movement or you can accidentally pull the crown out. Do the winding and the setting of the time during a period in the day when you’re relaxed and not in a hurry. Take off your watch from your wrist and do what you need to do.
  • Avoid dropping your watch. Yes, you are being cautioned, but accidents happen. The important thing is, at the back of your mind, you should never take your watch for granted, whether on your wrist or off it. The damage which the watch will incur will depend on the height from where your watch falls, the cushion and texture of the landed surface, and how the watch falls. You will be in luck if the watch drops from a short height, the surface landed on has a soft pillow and while falling, the bracelet of the watch is caught on a branch or on something protruding. You won’t believe your luck! The secret is, make the surroundings of your watch conducive to its safety. If you’re going to the beach, or if you’re going human catapulting, don’t wear your watch.
  • Service your mechanical watch regularly. It is designed to extend past your lifetime, but your day date mechanical watch needs to be serviced every 3 years. Normal wear and tear can impose some damage in them invisible to your eyes, but having them maintained at a reputable service center every few years will let you avoid expensive repairs on it if left unattended to.
  • Don’t set the time during the danger zone. The danger zone is the period between 9 pm and 3 am when the gears are in movement in anticipation of the switching of the date. Setting the watch during this period could cause a misalignment of the date window and break some parts in the movement. You will notice something wrong if the date changes early or after midnight (rather than the exact time when it strikes 12 midnight).
  • Don’t expose your watch to magnetic fields. Some innocent looking objects are actually villains in disguise. They include speakers, radios, and electronic devices (cellphones and tablets). They have magnetic fields and they could damage the movement of your watch. You might be surprised your day date watch has delays in changing the day and date and you have not realized that nearby, culprits abound. This is because the escapement which regulates the oscillations of your watch and makes the time accurate, has begun to act erratically. Some mechanical day date watches today have advanced, non magnetic materials as components. Check for the Gauss rating. Gauss is the unit of measure for the degree of magnetism.
  • Sometimes it’s foolishness that damages the watch. It’s always bad to wind a watch backwards rather than the correct forward movement. Improper setting of any complication on the mechanical day date watch can cause movement damage and also make the mainspring faulty.


Horology is the study of time and the art of making timepieces. Mechanical watches were the pioneers in horology. They started as grand watches and clocks. They became smaller timepieces when the need for accurate timekeeping grew in the Age of Exploration and travel. Mariners and travelers needed these tools to be able to keep track of time and the distance that they have journeyed correctly.

As time passed, and flying became very common, pilots required more accuracy and convenience when navigating their planes. Quartz wristwatches as we know them today were introduced. The advent of electricity and the ability to store it launched the popularity of the quartz watch which also had its own versions of day date watches.

But in a general sense, are still pricier, more collectible and more desired by watch aficionados. But in recent years, some quality quartz watches have grown in value. But they still have not exceeded the overall quality and financial value of mechanical watches.

These watches with mechanical movements usually take a long time to design, develop and launch. They are also made of several moving parts that have gone through several alterations to the next higher level, using silicon and parachrom hairsprings. New jewels are being put into place, new materials are being integrated that reduce wear and tear.

There will come a time when mechanical watches will only need servicing every 10 years because better metal alloys are being developed. The ongoing joke around the circles of mechanical watch adherents is that they are tending over the watch for the next generation.   Just imagine, a neophyte mechanical watch is in the price range of nearly $1,000.

But the practicality of quartz watches can’t be discounted. It is practical because its electrical power could be stored in their batteries and released on demand. They also have fewer moving parts (they are slimmer and lighter) and the power of the battery is good for 3 years. They don’t require much maintenance, because when they incur a major breakdown, hopeful after some years of use, it is much more practical to buy a new one rather than have it repaired.


But the beauty of the mechanical watch, especially the classic day date watch, is akin to precious gold and diamond jewelry. It doesn’t depreciate. It actually increases in value. Its moving parts are beautiful, larger, heavier and made of premium components.

When you wear a mechanical day date watch, you are wearing an engineering and classic masterpiece representing centuries of horological quality and innovation.

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