What is a GMT watch and how does it work?

The GMT function is a very useful complication, especially for those who travel frequently, as it allows you to quickly check both the time of the place you are visiting and the time of your home location.

What Does GMT Time Mean?

GMT stands for Greenwich Mean Time. This might be interpreted as your watch showing the time of the Greenwich meridian, but that is not the case; a GMT watch allows you to have multiple time zones (2 or more) on a single watch dial.

HOW CAN YOU TELL IF A WATCH IS A GMT?

GMT watches usually have two hour hands indicating the time, and the GMT hand is often red.
Some watches have a time scale on the bezel or within the dial itself.
The second time zone is indicated by a second hand that rotates around a 24-hour dial.

HOW TO USE THE GMT FUNCTION?

Standard wristwatch dials generally measure a 12-hour time interval. This means the hour hand makes two full rotations around the dial in 24 hours. To indicate GMT, the watch has an additional hour hand, typically arrow-shaped and a different color from the 12-hour hand. Unlike the hour hand, the GMT hand takes 24 hours to complete a full rotation around the dial, so it moves at half the speed of the other hand. The GMT time is read through the 24-hour bezel.

Besides its aesthetic appeal, GMT watches are especially practical for those traveling abroad. For example, a person traveling from Frankfurt to Sydney must constantly remember that the time difference from local German time is 8 hours, so upon arrival in Australia, they would always have to calculate the time based on German time. This becomes even more complicated if the person also has relatives in New York. In this way, a GMT watch helps avoid these kinds of problems very easily.

But let's look specifically at how to use the GMT function with this example on a watch that includes a separately adjustable hour hand.

You can set the different time zones at any time, whether still at home or after landing in Sydney at 8:00 PM. Simply set the GMT hands on the dial to European time (12:00). Then, also adjust the hour hand to Sydney local time (8:00 PM). To set New York time, rotate the 24-hour bezel (GMT hand) to the corresponding time for that city (6:00). With these brief and simple steps, you will now have three time zones simultaneously.

HOW DID GMT WATCHES ORIGINATE?

As the Earth rotates around the Sun, the light it receives shifts, and although this fact is now well known, until the mid-19th century it was unknown, and there was no awareness of time zone changes worldwide.
In Germany alone, each principality had its own time. Over time, with the arrival of railways, the existence of so many time zones caused chaos since more than 30 different time zones had to be considered.
In 1884, after endless negotiations, an agreement was reached to divide the Earth into 24 time zones, and the Greenwich meridian, GMT, was established as the "zero" hour.
In the 1960s, this was replaced by UTC, Coordinated Universal Time, whose main feature is the division of the day into 24 hours based on time zones.
The GMT format was invented in watchmaking so travelers could quickly know the time anywhere in the world. These watches quickly became popular in aviation, as they allowed pilots to see both the origin and destination times.
GMT watches based on 24 hours are widely used in navigation and communication protocols to avoid confusion.

WHY DO YOU NEED A GMT WATCH?

Today, traveling has become easier, and thanks to the GMT function of the watch, you can know the time in different countries.
It is important to remember that the watch must be set, so with just a glance you can know the time in different parts of the world.