Scientists use the Greenwich Mean Time (GMT) as a reference point to calculate the time in different locations. Formerly known as the Universal Time Coordinated (TC), this zero hour can determine the time in any location in the world by adding or subtracting hours from it depending on whether you’re moving eastwards or westwards of this reference point. 

Fortunately, you don’t have to remember a bunch of complex calculations to work out the time in multiple locations. Using GMT watches, you can easily track the time in your location and another location of your choice. 

What is a GMT Watch? 

A GMT timepiece is a type of travel watch with a complication that allows it to simultaneously track time in multiple locations or time zones. This feature makes GMT watches a popular choice for people who travel a lot and professionals whose work requires them to be (or know the time) in different locations. 

GMT watches were invented in the 1950s during the early days of the Transatlantic flight. Pilots and passengers were flying on long-haul routes across multiple time zones for the first time in history. To track the local time and the time at their destination, Rolex designed the GMT complication. Thus, the Rolex GMT-Master with the ‘Pepsi‘ bezel was created, marking the birth of one of the most iconic complications in the horological world. 

Key Components of a GMT Watch

The main feature of a GMT watch that sets it apart from regular timepieces is the addition of an extra hour hand to the dial along with a 24-hour scale. This extra scale is printed on a rotating bezel or between the regular indices on the dial. The hour hand typically comes in a different shape or colour to give the dial more legibility. 

In a conventional watch, the movement train moves the hour hand around the dial every 12 hours. To create a GMT watch, the watchmaker adds an extra hour hand designed to run half as fast as the main hour hand. This way, it moves around the dial in 24 hours instead of 12 hours. The tip of the hour hand points to its corresponding time on the 24-hour scale added to the watch bezel. 

For instance, in the iconic Rolex GMT-Master watch, the GMT hand points to a 24-hour scale on the bezel. This bezel was also colour-coded with blue to correspond to night-time hours and red for daylight. The bezel was designed to rotate bidirectionally so the wearer can easily set any hour to conform to the GMT hands. This way, you can instantly track a second time zone with the bezel while the main dial continues to track the standard time.  

How to Set and Read a GMT Watch

Different watchmakers have created various kinds of GMT watches. While they all operate on a common principle, the process for setting and reading the time with them varies. So, how does a GMT watch work? 

The standard hour hand and GMT hand were connected in the original watches so that you couldn’t set one without the other. In this case, you must align the bezel to the main dial at the 12 o'clock position. 

To determine the time in a different city, you have to rotate the bezel either to the left or right depending on the location of the second time zone relative to yours (rotate to the right if the timezone is behind and rotate to the left if the timezone is ahead. 

Most modern GMT watches have a more advanced mechanism mainly characterised by an independent GMT hand. This allows you to set the hour hand while the GMT hand stays static or vice versa. 

To set this type of GMT watch, you keep the 24-hour scale in its starting position aligned with the dial’s main 12 o’clock scale. Then, you can set the hour hand to the current local time using the 12-hour scale. Finally, align the GMT hand to the 24-hour scale for the second time zone you wish to track. 

Types of GMT Bezels

The rotating bezel has become a standard part of modern GMT watches and an essential feature for setting and telling the time. However, a few models, like the Rolex Explorer II, Grand Seiko SBGM253, and Christopher Ward C65 Dune GMT, have fixed bezels. These models still have a 24-hour hand pointing to a scale on the dial, while the fixed bezel is used as a reference point for reading the second time zone. 

The GMT watches with rotating bezels are technically more advanced because they allow you to track a third-time zone. You must set the GMT hand to your current timezone while the standard hour hand is set to the local time. You can then set the watch to track a third-time zone by rotating the bezel forward or backwards depending on the location’s time zone in reference to the GMT. 

The bezel and GMT hand will be used to read the third time zone by setting it this way. The hour hand and the main dial will tell the local time, while the second time zone will be determined by rotating the bezel back. 

Practical Uses of a GMT watch

The Rolex GMT Master was originally commissioned for pilots working for the Pan American Airway. This, along with many other GMT watches of the 1900s, was primarily used by pilots to monitor the time they flew across the globe. 

Over time, the Rolex GMT became popular with frequent fliers, especially those who travel often for work. Such people needed to track their time at home and in their current location. This complication is particularly useful for families in different time zones. It makes it easy to tell what time of the day it is in their location so you can easily tell when to call them. 

However, even though GMT watches were built for travellers, you don’t have to travel anywhere to use one. Businessmen and professionals (such as forex traders) who need to schedule or monitor international market openings in different countries may also get a GMT timepiece. 

Another lesser-known use of the GMT timepieces is that they can be used as a compass. You can set the GMT hand of the watch to your local time and point it towards the sun. The GMT hand will be pointing north or south, depending on whether you’re in the Northern or Southern Hemisphere. 

Shop GMT Watches at Bezel

As one of the most popular and relatively affordable complications, GMT watches are commonly sought by collectors and everyday buyers. These luxury watches are readily available both in the retail and pre-owned markets. 

Bezel's got you covered if you’d like to buy a pre-owned GMT timepiece. Our catalog includes some of the most impressive GMT watches, including Rolex GMT Master and Master II watches and similar Tudor GMT watches. We also have GMT models from notable watchmakers like the Frank Muller GMT Transamerica, Grand Seiko Hi-Beat Automatic GMT, Breitling GMT Midnight, and more.

You can browse the Bezel website or download the Bezel App to find these and other GMT watches. The timepieces we sell are all authenticated, and you can find some of the most elusive models in our catalog. 

The bezel catalog is organized so you can search and filter by brand, price, case size, material, and other criteria. If we don’t have exactly what you’re looking for right now, you can contact us directly. Get started now to find a GMT timepiece for your collection.