GMT Watches
GMT Watches
One watch, multiple time zones.
About GMT Watches
Capable of simultaneously keeping track of different time zones, GMT watches are frequently considered to be one of the most practical kinds of timepieces available. While they were originally created for airplane pilots to use on long flights, GMT watches are now worn by countless individuals all over the world who appreciate them for their useful features and travel-ready functionality.
What Is a GMT Watch?
A GMT watch is a specific kind of timepiece that is able to display two or more time zones, with at least one of them presented in a 24-hour format. Unlike other types of watches that are able to track multiple time zones, the 24-hour display is a requirement for GMT watches because it functions as a reference point and allows them to calculate any other time zone in the world by knowing the number of hours either ahead or behind of the reference time.
What Does GMT Mean?
GMT stands for “Greenwich Mean Time” and this is the time of day at the Royal Observatory in Greenwich, London that serves as the ‘zero hour’ standard and the basis for all other timezones. While the term for this zero-hour reference time was updated to UTC (which stands for “Universal Time Coordinated”) in 1972, most watch manufacturers still use the term “GMT” due to the fact that the complication itself significantly pre-dates the establishment of Coordinated Universal Time. Technically speaking, GMT and UTC are not the same thing, because GMT is a timezone, while UTC is a time standard. However, since both represent the time of day at the zero-hour point, the two terms are often used interchangeably within casual discussion.
While the very first dual time and worldtime complications were
created before the advent of the wristwatch itself, the GMT watch as we know it today started
its life in the mid-1950s with the rise of the purpose-built tool watch.
The very
earliest GMT watches were created for professional pilots and featured 24-hour dials, where the
hour hand makes a single complete rotation once per day. By fitting these watches with rotating
bezels marked with 24-hour scales, pilots could easily keep the hands set to GMT time and simply
turn the bezel to display the time in their current location.
The History of GMT Watches
However, within just a few years of the very first GMT
watches making their inaugural appearances, this innovative style of travel-ready timepiece
received a major update in the form of an additional hour hand being added to their dials. Now
fitted with a secondary 12-hour hand, this follow-up generation of GMT watches allowed pilots to
read the time in a traditional 12-hour format without sacrificing any of the GMT capabilities of
their 24-hour dial predecessors.
The next major innovation arrived in the early 1980s,
and it enabled the two hour hands to be set independently from each other. This drastically
alters the functionality of modern GMT watches and enables them to display two different time
zones with just their dials and hands, leaving their rotating bezels free to display a third.
Since the 24-hour bezel is no longer a requirement for GMT functionality, today’s GMT watches
are free to to take on a wide variety of different styles, making this highly useful
complication even more practical than ever before.
The History of GMT Watches
However, within just a few years of the very first GMT watches
making their inaugural appearances, this innovative style of travel-ready timepiece received a
major update in the form of an additional hour hand being added to their dials. Now fitted with
a secondary 12-hour hand, this follow-up generation of GMT watches allowed pilots to read the
time in a traditional 12-hour format without sacrificing any of the GMT capabilities of their
24-hour dial predecessors.
The next major innovation arrived in the early 1980s, and it
enabled the two hour hands to be set independently from each other. This drastically alters the
functionality of modern GMT watches and enables them to display two different time zones with
just their dials and hands, leaving their rotating bezels free to display a third. Since the
24-hour bezel is no longer a requirement for GMT functionality, today’s GMT watches are free to
to take on a wide variety of different styles, making this highly useful complication even more
practical than ever before.
With that in mind, not all watch clasps are the same, and different styles can offer different features and appearances, in addition to significantly impacting the overall fit and feel of your timepiece.
Different Types of GMT Watches
Within the greater category of GMT watches, you will find a number of different approaches to
achieving the same core GMT functionality. The preferred method for many brands is to have four
centrally-mounted hands, with one 12-hour hand and one 24-hour hand. However, you will also find
GMT watches that use rotating discs or even sub-dials for displaying their secondary time
zones.
Even among the variety with four centrally-mounted hands, some have their two
hour hands linked together like the very earliest GMT watches, while others can be independently
adjustable. Furthermore, some allow for independent adjustment of the 24-hour hand, while others
enable the 12-hour hand to be set independently without disturbing the other hands or disrupting
the timekeeping of the watch.
True GMT vs. Office GMT Watches
One of the distinctions between different types of GMT watches that has come up in recent years is that of True GMT watches vs. Office GMT watches. While both models are actually GMT watches with four centrally-mounted hands, a true GMT will let you jump the 12-hour hand backwards or forwards in one hour increments, while an office GMT will allow for independent adjustment of the 24-hour hand and the date display.
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The Most Famous GMT Watches
The Glycine Airman is often credited with being one of the first known examples of a purpose-built GMT wristwatch, and it debuted in 1953 with a 24-hour display paired with a rotating bidirectional bezel marked with a 24-hour scale. The hour hand only made one full rotation around the dial each day, and by turning the bezel to correspond with the time difference, pilots could easily read a second time zone by looking at the hour hand’s position against the bezel.
Read MoreHow Does a GMT Watch Work?
The specific style of GMT watch, along with how it
presents its time zones can influence the different ways that it functions
and operates. However, the versions with four centrally-mounted hands all
function in a relatively similar overall manner. The hours, minutes, and
seconds of the day are displayed by three of the four centrally-mounted
hands, just like any other watch.
The remaining fourth hand is the
24-hour hand, which can be used to display a secondary timezone against a
corresponding scale on either the dial or bezel. On the older style of GMT
watches that have their two hour hands linked, the 24-hour hand will display
the same time as the 12-hour hand but it will present it in a 24-hour
format, making one full rotation around the dial each day.
How to Read a GMT Watch
Since the 12-hour hand makes two full rotations each
day, you read the time zone presented by the 12-hour hand against the
regular hour markers on the dial, just like any other wristwatch. However,
since the 24-hour hand only makes one full rotation, you will read it
against a corresponding 24-hour scale on either the dial or bezel.
Since the 24-hour hand presents the time in a 24-hour format, there
is no way to confuse AM versus PM hours in your secondary time zone.
Additionally, if your watch has a rotating 24-hour bezel, you can turn it to
correspond with the number of hours offset, either ahead or behind of the
time zone displayed by your 24-hour hand, and the third time zone will then
be shown by the value indicated by your 24-hour hand’s position against the
sale on your bezel
How to Use a GMT Watch
There are many different ways to use a GMT watch, but
one of the most practical is to set the 24-hour hand to GMT/UTC and then
have the 12-hour hand on your watch display the time in your current time
zone. This will enable you to read the time in your current location, just
like you would on any other clock or wristwatch, but it also offers the most
flexibility when it comes to calculating the time in different parts of the
world.
Time zones are often listed by their number of hours offset from
GMT/UTC. For example, Swiss time is often written as GMT+2, while you will
often see Pacific Standard Time written as GMT-8. Keeping your watch’s
24-hour hand set to GMT will let you have an easy and constant point of
reference, and if your watch has a rotating bezel, you can easily turn it to
correspond with the number of hours offset from GMT to tell the time
anywhere in the entire world.
How to Set a GMT Watch
Setting instructions will differ by model, but many
operate in a similar overall manner. Among the variety that have
independently adjustable hour hands, the first setting position on the crown
will set one of the two hour hands and/or the date display, while the second
will rotate all of the hands and set the time, just like any other watch.
On the versions that allow for independent adjustment of the
12-hour hand, the first setting position will typically allow you to jump
the hand forwards or backwards in one-hour increments. On the versions that
allow for adjustment of the 24-hour hand, the most common method of
operation will let you advance the 24-hour hand by turning the crown in one
direction, while rotating it in the other will allow you to set the date.
Buying a GMT Watch
When it comes to buying a GMT watch, there are many different options available and brands continue to produce new offerings each year. Although everyone always wants the best GMT watches possible, what is “best” for one person might not necessarily be best for another with a different lifestyle and different requirements from their timepiece.
Finding the Right GMT Watch for You
The best GMT watch for you is the one that is best suited to your individual lifestyle and budget. For example, someone who frequently travels and always needs to reset their watch when they reach a new destination will likely find a true GMT model most useful, while someone who frequent spends their days communicating with people in other parts of the world but who isn’t actually changing location themselves will almost certainly find a caller GMT watch to be the more practical option.
Finding the Right GMT Watch for You
The best GMT watch for you is the one that is best suited to your individual lifestyle and budget. For example, someone who frequently travels and always needs to reset their watch when they reach a new destination will likely find a true GMT model most useful, while someone who frequent spends their days communicating with people in other parts of the world but who isn’t actually changing location themselves will almost certainly find a caller GMT watch to be the more practical option.
The Formex Reef GMT Automatic
Chronometer 300M
Formex’s own flagship GMT watch is the Formex Reef GMT Automatic Chronometer 300M, which expands upon the core platform of the popular Reef dive watch and its signature interchangeable bezel system. The Formex Reef GMT takes this up a notch with a sapphire display caseback and the ability to simultaneously display three different time zones.