Among the various watch functions, the "GMT" function is particularly popular. Originally developed for international airline pilots, the GMT function is now useful in global business and travel settings, and its ability to add a stylish accent to a watch's design also contributes to its popularity. This article will introduce the basics and usage of the GMT function, along with some recommended GMT watches.
Text by Kento Nii
[Article published on January 19, 2026]
What is the GMT function on a wristwatch?
In the context of watches, the GMT function generally refers to a mechanism that allows for the simultaneous display of the time in two different time zones.
The most basic GMT function is a type that, in addition to the regular time display hands, has a "GMT hand" that completes one rotation in 24 hours, and a corresponding 24-hour scale. By combining the independent operation of the hour hand or the GMT hand, which can be operated in one-hour increments, it is possible to reflect the time difference with any region and display both the current time and the second time zone.
Inspired by the early spring seasonal word "snowdrop," this GMT watch features a white dial that depicts snowdrops sparkling in the spring sunlight. A single pull of the crown allows the hour hand to be independently operated, enabling setting of any desired time. Automatic movement (Cal. 9S66). 35 jewels. 28,800 vibrations/hour. Power reserve approximately 72 hours. Stainless steel case (39.5mm diameter, 14.1mm thickness). Water resistant for everyday use. 704,000 yen (including tax).
Furthermore, GMT watches with rotating bezels featuring a 24-hour scale are also widely popular. This type allows the wearer to simultaneously track the first time zone indicated by the hour hand, the second time zone indicated by the GMT hand, and a third time zone created by combining the GMT hand and the rotating bezel, by combining the rotation of the bezel with the operation of the hour hand. Many of these bezels also feature fashionable two-tone designs to distinguish between day and night, making them a popular feature in GMT watches.
Other methods for displaying multiple time zones include those where the GMT hand completes a full rotation in 12 hours, similar to the hour hand, and those where, instead of placing a GMT hand in the center, one or more sub-dials with hour and minute hands are provided within the main dial to display home time and local time. The latter is seen in multi-function quartz watches and professional-grade pilot watches, and allows for a more intuitive distinction between the two time zones.
What exactly is "GMT"?
The name GMT is an abbreviation for "Greenwich Mean Time." This is the world standard time adopted in 1884, and it refers to the time based on the prime meridian (0 degrees longitude) that passes through the Greenwich Observatory in England.
This standard is used as a universally accepted measure in global transportation, communications, finance, and other fields where strict time management is required. For example, we Japanese express time differences with other countries as +2 hours, -4 hours, etc., based on Japan Standard Time, but Japan's time from Greenwich Mean Time is shown as "GMT+9". By understanding this standard and the time differences between regions worldwide, flexible cooperation between countries becomes possible, even in international businesses and initiatives.
Currently, the most widely used international standard time is "UTC (Coordinated Universal Time)." This is based on the "atomic clock," considered the most accurate clock in the world, and has been fine-tuned with "leap seconds" to keep the discrepancy with the Earth's rotation (which completes one rotation in approximately 24 hours) to less than one second (leap seconds are scheduled to be abolished by 2035). For this reason, some brands refer to their GMT function as "UTC," but the former is the name that is generally more widely used.
Basic operation of the GMT function
Despite its GMT function, it's surprisingly easy to operate. Many high-end models, in particular, allow you to adjust the time zone without stopping the second hand, maintaining excellent accuracy.
A newly purchased GMT watch will often have the GMT hand and hour hand pointing to the same time. If the hour and GMT hands are not synchronized and are pointing to different times, it's easier to set the GMT hand to midnight (0:0) and then the hour hand to midnight to establish a clear reference point for subsequent operations.
Taking the example of setting the time zone when traveling from Japan to Switzerland, with a typical four-hand watch (hour, minute, second, and GMT hand), you would first set both the GMT hand and the hour hand to Japan time. Then, pull out the crown to a certain position and set only the hour hand to the local Swiss time. Since the time difference between Japan and Switzerland is 8 hours in winter, you would need to move the hour hand back 8 hours. This allows you to keep track of Japan time with the GMT hand while checking the local Swiss time with the hour hand. Note that there are also types of watches where the GMT hand moves independently of the hour hand.
Recommended models that let you experience the appeal of the GMT function.
Below, we introduce a selection of recommended watches with GMT functionality. This time, we've chosen everything from classic timepieces to unique models equipped with multiple functions in addition to GMT.
Rolex "Oyster Perpetual GMT-Master II" Ref. 126710BLNR
Rolex, a key player in establishing the waterproof technology for modern watches, is also known as one of the pioneering brands in GMT watches. Its history dates back to the GMT-Master, developed in 1955.
The 1950s were a time when advancements in aviation technology led to the widespread adoption of international air routes. The GMT-Master was a wristwatch designed for these pilots. It was originally manufactured at the request of Pan American World Airways, the leading American airline at the time. Initially, this collection allowed the wearer to simultaneously check the time in both the departure and arrival locations by operating a rotating bezel, but after the GMT-Master II update, the hour hand could be operated independently, allowing the wearer to track up to three time zones.
Automatic winding (Cal. 3285). 31 jewels. 28,800 vph. Power reserve approximately 70 hours. Oystersteel case (40mm diameter). Water resistant to 100m.
From the current lineup of the "Oyster Perpetual GMT-Master II," we've selected the popular model Ref. 126710BLNR, affectionately known as "Batman." This watch features a black dial combined with a blue and black Cerachrom bezel insert, which is the origin of its nickname. The GMT hand is colored in a vibrant blue that matches the bezel, serving both to enhance readability and as an accent on the dial. Its predominantly black appearance makes it easy to wear in both private and business settings.
The Oystersteel case has a diameter of 40mm and is available with either an Oyster bracelet or a five-link Jubilee bracelet. The clasp has a robust structure that prevents accidental opening, and an extension link allows for approximately 5mm of size adjustment using the clasp alone.
The movement is the Cal.3285, which boasts a power reserve of approximately 70 hours. This in-house movement features a blue Parachrom hairspring and a high-performance Paraflex shock absorber, resulting in superior magnetic and shock resistance.
Bell & Ross BR-03 GMT Compass, Ref. BR0393-COM-ST/SRB
From Bell & Ross, known for its functionally beautiful watchmaking inspired by aircraft cockpit clocks, we feature the "BR-03 GMT Compass," a limited edition of 500 pieces worldwide. Inspired by the compass, this timepiece combines playful expression with the stoicism of a tool watch.
Automatic movement (Cal. BR-CAL. 303). 25 jewels. 28,800 vibrations/hour. Power reserve approximately 54 hours. Stainless steel case (42mm diameter, 12.3mm thickness). 100m water resistance. Limited edition of 500 pieces worldwide. 671,000 yen (tax included). (Inquiries) Bell & Ross Ginza Boutique Tel. 03-6264-3989
The dial features a thick hour hand, a single minute hand, and a bidirectional seconds hand in gray and light blue. The highlight, the GMT function, consists of a dynamic diamond-shaped GMT hand resembling a compass needle and a black and blue two-tone bezel. Each hand is color-coded to stand out on the dial, and its shape is clearly differentiated, ensuring accurate time reading.
Furthermore, this model features compass markings on the flange at 15° intervals, allowing it to be used as a simple compass to determine direction on clear days. This design further activates the GMT watch's unique function of pointing the hour hand towards the sun during the day, causing the GMT hand to point north.
The square case features Bell & Ross's signature design, combining a square with a circle, and has screws at the four corners of the front. It has a diameter of 42mm, a thickness of 12.3mm, and is water-resistant to 100m. The combination of polished and satin finishes softens its rugged appearance, and combined with the lightweight black rubber strap, it's a watch that's easy to choose for everyday wear.
Inside, it houses the Cal.BR-CAL.303 automatic movement, which has a power reserve of approximately 54 hours. The case back is solid.
Ball Watch "Roadmaster M Model A" Ref. DA9100C-S1J-BKR
Ball Watch is a brand founded in the early 20th century by Webster Clay Ball. He is known for his significant contributions to establishing the strict timetables of American railroads at the time. From this brand, we introduce the "Roadmaster M Model A," a multi-functional watch limited to 333 pieces worldwide, which combines a mechanical alarm function and a GMT function.
Automatic winding (Cal. RR7379). 31 jewels. 28,800 vibrations/hour. Power reserve approximately 45 hours. Stainless steel case (41mm diameter, 15.2mm thickness). 100m water resistance. Limited edition of 333 pieces worldwide. 880,000 yen (tax included). (Inquiries) Ball Watch Japan Co., Ltd. Tel. 03-3221-7807
This model manages to handle the sheer volume of information due to its multi-functionality through a multi-layered dial. A disc for setting the alarm time is located in the center, a red GMT hand surrounds it, and a 24-hour display is positioned on the flange. The combination of this GMT hand, the scale on the flange, and the rotating bezel with a red and black two-tone ceramic insert allows for the display of up to three time zones.
Furthermore, the indices and hands on the dial feature Ball Watch's signature "self-illuminating micro gas lights," ensuring excellent visibility even in dark conditions.
The case and bracelet are made of high-quality 904L stainless steel. Boasting 5000G shock resistance and 100m water resistance, it features a robust construction befitting its thick 15.2mm case. The case has two crowns on the side; the crown at 2 o'clock is used for time adjustment and GMT hand operation, while the crown at 4 o'clock is used for alarm setting. When the set time arrives, a hammer strikes a gong on the outer edge of the movement, signaling the time.
The movement is the Cal.RR7379, which boasts a power reserve of approximately 45 hours. A particularly noteworthy feature of this model is the ability to observe the operation of its alarm mechanism through the transparent case back.
