GMT Watches Explained
The time has come to look at GMT watches - what they are, how they work, and why you probably need one in your collection.
As you probably know, a GMT watch is capable of keeping track of two or even three time zones at the same time. That is achieved by adding an extra hour hand in addition to the seconds, hour, and minute hands usually found on most watches.
Whilst the standard hour hand takes 12 hours for one full rotation of the dial, the fourth hand completes one lap every 24 hours. Add a rotating 24-hour bezel, and suddenly you can track three time zones at the same time.
There are several design interpretations of the GMT concept, and before we discuss the two types of GMT movements, let’s look briefly at where it all began.
A Short History of the GMT Watch
In the 1950s, intercontinental flights became commercially viable. Suddenly an Atlantic crossing took hours rather than days. Pilots were moving through multiple time zones in a single shift and needed to track time at home base, time at destination, and the reference time used in aviation.
This was long before digital devices made such information instantly available. A reliable mechanical instrument capable of tracking multiple time zones was not a luxury - it was a necessity.
The first watch to offer dual time zone functionality was the Glycine Airman. It featured a 24-hour dial with a matching 24-hour hand, along with minute and second hands. Furthermore, it had a rotating 24-hour bezel that could be locked and unlocked via a second crown positioned at 4 o’clock.
With this configuration, three time zones could be tracked simultaneously - a remarkably practical solution for the time.
It was however not Glycine that gave GMT watches their broader appeal. Pan Am, pioneers of long-distance commercial aviation, required watches that could provide their pilots with crucial timekeeping information as they travelled through different time zones.
In 1954 Rolex answered the call with the GMT-Master - now an icon, and probably the first watch that comes to mind when you hear the word ‘GMT’. Unlike the Airman, the GMT-Master featured a conventional 12-hour hand alongside a 24-hour hand, and a bi-directional rotating bezel that moved in one-hour increments without needing to be unlocked.
Since its introduction, the GMT-Master - visually not far removed from the Submariner - has become a symbol of wanderlust, long-haul travel and the jet-setting lifestyle. Rolex arguably leads the way, and over the years the GMT-Master has evolved both technically and visually, available in various materials and bezel colours.
Today, most major watch brands offer their interpretation of the GMT concept.
How Does a GMT Watch Work?
To understand GMT properly, you need to know about Coordinated Universal Time.
Coordinated Universal Time - or UTC, as it is somewhat illogically shortened - is the primary time standard by which the world regulates clocks and time. It is within about one second of mean solar time at 0° longitude (the Greenwich meridian) and is not adjusted for daylight saving time. It effectively replaced Greenwich Mean Time (GMT) as the global time standard.
All airborne vessels operate on UTC. When you are onboard a plane, UTC remains constant regardless of where you are in the world.
This is where the GMT watch becomes especially useful.
GMT Movements
Several movement manufacturers produce GMT calibres, both mechanical and quartz regulated. Broadly speaking, there are two types of GMT movements:
The Traveller’s GMT
The Caller GMT (also known as the Office GMT)
The Traveller’s GMT Movement
As the name suggests, this is the superior solution for frequent travellers who regularly cross time zones.
A Traveller’s GMT displays local time centrally with hour and minute hands and date. It also features a 24-hour hand, so visually there is no obvious difference between a Traveller and a Caller GMT. You would not know which one you have until you operate the crown.
The key difference lies in how the watch adjusts.
A Traveller’s GMT allows you to independently move the 12-hour hand forwards or backwards in one-hour increments. The 24-hour hand typically remains set to your home time.
Why is that smart?
Let’s look at an example:
Assume you are based in London and you board a flight to New York at 9pm on the 6th of January. Before departure, both your 12-hour hand and 24-hour hand show 9pm (2100 hours), and the date window indicates January 6th.
When you land six hours later, your watch shows 3am and the date has advanced to January 7th - still London time. However, New York operates at GMT -5 hours.
You now adjust the 12-hour hand backwards by five hours. The watch jumps from 3am to 10pm local New York time. Crucially, as you adjust the hour hand backwards past midnight, the date automatically corrects itself back to January 6th - which it still is in New York.
The result:
The 12-hour hand shows local New York time (10pm).
The date is correct.
The 24-hour hand still indicates London time (3am).
Until recently, Traveller’s GMT watches were typically priced north of £3,000. That changed significantly with the introduction of movements like the Miyota 9075, which brought true traveller functionality into a far more accessible price bracket.
The Caller GMT Movement
The Caller GMT - sometimes referred to as the Office GMT - is ideal for people who operate internationally but remain mostly in one time zone.
In essence, the Caller GMT is a standard three-hand movement with a fourth 24-hour hand added. The 12-hour hand remains fixed as your primary local time. Instead, the 24-hour hand can be adjusted independently to track another time zone.
Let’s assume you are in London and it is 12 noon. Your colleagues in San Francisco operate at GMT -8 hours, which makes it 4am there. You adjust the 24-hour hand to 0400 hours. If you also wish to track New York (GMT -5), you can rotate the bezel anti-clockwise by three hours, and you now have three time zones visible at a glance: London, New York and San Francisco.
When travelling with a Caller GMT, the approach differs from the Traveller example above. You can either:
Leave the 12-hour hand set to your home time and adjust the 24-hour hand to local time, or
Reset the entire watch if staying abroad for an extended period.
The Caller GMT is mechanically simpler, and that is reflected in the price. Popular automatic GMT movements such as the ETA 2893-2, Sellita SW330-1/-2, Seiko NH34 and Miyota 9075 dominate the market today - though only the latter offers true traveller-style functionality.
Which Should You Choose?
In today’s market, the gap between the two has narrowed significantly.
A true Traveller’s GMT is no longer reserved exclusively for the high-end segment, but it will still command a premium. Visually there is no difference between the two types. Both allow you to track multiple time zones. The difference lies purely in functionality and convenience.
In a perfect world, a Traveller’s GMT is the most elegant solution. In reality, a Caller GMT is more than capable for most people.
A GMT watch is not just for pilots or international executives. It is for anyone whose life stretches beyond one place. If your family, work or ambitions cross borders - physically or mentally - a GMT makes quiet sense.
Enoksen and GMT
We introduced our first Enoksen GMT watch at the beginning of 2023. We had been searching for a suitable movement for years - something automatic, reliable, made by a reputable manufacturer, and affordable.
With the introduction of the excellent Seiko NH34, the search was finally over.
The NH34 builds on the proven NH35 architecture - a movement we have used since the early days of the company and found to be ultra-reliable and easy to regulate.
Our GMT watch is called the Roam E07/A. It is based on the popular 40.8mm case already used for the Dive E02 models. Like the Dive E02, it offers:
300m water resistance
Anti-reflective sapphire crystal
Many affordable GMT watches borrow diver-style bezel mechanics - 60, 90 or 120 clicks and often uni-directional rotation - which is not technically correct for a GMT.
We wanted more than that.
Roam E07/A features a bi-directional ceramic bezel with 24 clicks - the correct way to execute a genuine GMT. It is powered by the Seiko NH34 and is available on our vulcanised Tropic rubber strap or a tapered Oyster-style steel bracelet.
In 2025 the Roam E07/B followed. A slightly different take on the classic GMT style.
Explore the watches here.