GMT Watches Explained: Function, History, and Models Worth Your Time

Who invented the GMT watch?

Before we dive into what GMT watches actually are, let’s start with who invented the watch. The story begins in the 1950s. Pan Am, one of the world’s most iconic airlines, needed a tool watch for their pilots to track both local and home base time during transatlantic flights. Fun fact: Glycine technically beat Rolex to the punch with the Airman in 1953. But it was the Rolex GMT-Master, developed a year later with Pan Am, that became the benchmark. It was an instant hit with the aviation world and eventually with collectors. And that red-and-blue bezel? Pure design genius. It told time and told a story, day vs night, east vs west, pilot vs passenger.

What is a GMT Watch?

A GMT watch displays two time zones simultaneously using a 24-hour hand that rotates once per day. The main hour hand shows local time, while the GMT hand points to a second time zone, often on a separate bezel. This feature is useful for travelers and professionals coordinating across time zones.

GMT stands for Greenwich Mean Time, which used to be the global standard for navigation and timekeeping. These days, we use UTC (Coordinated Universal Time) more often, it’s the modern standard used in aviation and tech, with leap seconds added for precision, but “GMT” still lives on in the watch world, and with good reason. The defining feature is the fourth hand, which circles the dial every 24 hours. It works in tandem with a 24-hour scale, usually located on a bezel or inside the dial, and lets you track an alternate time zone at a glance. Unlike a standard watch, a GMT tells you not just what time it is, but what time it is somewhere else. Instantly. But the appeal goes far beyond airports, GMTs are just as useful for remote work, global teams, or simply staying connected to people you care about.

How a GMT Watch Works (And Why It’s So Clever)

Mechanically, a GMT watch runs like a standard three-hand automatic, but with an added 24-hour hand. That GMT hand completes one full rotation per day and points to a 24-hour scale, either on the dial or on a rotating bezel. Let’s break it down with a real example. Say you’re based in Berlin and want to keep track of Tokyo time. If it’s 10:00 AM in Berlin, you know Tokyo is eight hours ahead, that’s 6:00 PM. You simply set the GMT hand to reflect 18 on the 24-hour scale. Now, every time you check the watch, you’ve got both time zones at a glance. Just keep in mind: using the rotating bezel to track a third time zone only works on some GMTs, typically those with caller-style movements. If your watch has a rotating bezel, you can even shift the scale to track a third time zone. It’s a small trick, but super handy for people who manage calls across continents.

How to Read a GMT Watch Bezel

Most GMT bezels are split between day and night, typically in two colors. For example, the Rolex GMT-Master II “Pepsi” has blue for night hours (18:00 to 6:00) and red for daytime (6:00 to 18:00). That’s not just for looks, it visually separates AM and PM in your second time zone, helping you avoid a very awkward midnight Zoom call. But not all GMTs follow the classic two-tone style, some models, like the “Bruce Wayne” or “Root Beer,” offer darker or more modern color schemes that still follow the same logic. You read the bezel by looking at where the GMT hand points on the 24-hour scale. If it’s pointing to 14, that means it’s 2:00 PM in your second time zone. The local time is still shown by the regular hour hand.

Caller vs Traveler: The Two Types of GMT Watches

There are two kinds of GMT movements, and this part actually matters for usability. A caller GMT lets you independently adjust the 24-hour hand, while the main hour hand stays fixed. It’s great if your base location stays the same and you’re monitoring someone else’s time zone,like a remote team or family abroad. A traveler GMT is the opposite: the local hour hand jumps forward or backward in one-hour steps, while the GMT hand stays put. It’s ideal if you’re the one flying between time zones. No need to reset the whole watch, just click your way into the right time. On some GMTs, especially higher-end models, the bezel rotates in 24 precise clicks, one per hour, making it easier to track that third time zone with accuracy. Most Seiko and microbrand GMTs are caller GMTs. Rolex, Tudor, and Omega use the traveler setup. Traveler GMTs are more expensive to manufacture, which is why you typically find them in higher-end brands. Caller GMTs are simpler and more affordable, but still highly practical.

GMT vs Dual Time vs World Timer: What’s the Difference?

A dual-time watch usually has a small sub-dial showing a second hour format, often in 12-hour time. It works fine, but it lacks the intuitive clarity of a GMT’s fourth hand and 24-hour scale. World timers take it to another level. They show the time in all 24 major time zones at once, typically using a rotating city ring. Think of icons like the Patek Philippe World Time or the Overseas World Time from Vacheron Constantin, they’re beautiful, but more display piece than daily driver. While incredibly cool and visually complex, they’re less hands-on, more of a passive complication than an interactive one. A GMT gives you control. You set what matters to you. In short: a GMT is active, a dual-time is simplified, and a world timer is broad but mostly passive.

Why Do Pilots Wear GMT Watches?

You’ve probably seen GMT watches pop up on the wrists of pilots in movies, lounges, and vintage travel posters. But it’s not just style, there’s history behind it. When you’re flying across time zones, local time changes constantly. But airline schedules, air traffic control, and communications often stick to a fixed global reference like GMT or UTC. Pilots rely on that second time zone to coordinate operations, avoid confusion, and stay in sync. Having a GMT function on the wrist meant less mental math and fewer mistakes mid-flight. That kind of practical, time-saving utility is exactly why GMT watches became cockpit essentials, and why they still feel purposeful today. And even if you’re not flying at 35,000 feet, the beauty of a GMT is that its usefulness doesn’t stop when the wheels touch down.

The only thing does feels weird: the first ever pilot's watch was the Cartier Santos Dumont, and that's no GMT watch!

How to Set a GMT Watch?

Setting a GMT watch is easier than it sounds, it just depends on the type of movement inside. If you’ve got a traveler-style GMT, you’ll usually start by setting the GMT hand to your home time (the time you want to keep constant). Once that’s set, you can adjust the local hour hand separately in one-hour jumps, no need to stop the watch. It’s perfect for travelers hopping time zones without resetting everything. With a caller-style GMT, it works the other way around. You set the main time like any standard watch, then adjust the 24-hour GMT hand to match the second time zone you want to track, ideal if you're staying put but need to keep an eye on a remote office or family abroad. And if your GMT has a rotating bezel, you can even track a third time zone. Just twist the bezel so the GMT hand points to the correct offset. It’s a clever little trick for managing global calls or keeping tabs on multiple cities, all from one dial.

How Accurate Are GMT Watches?

Accuracy depends on the movement type:

• Mechanical GMTs (e.g., Rolex, Omega): COSC-certified, typically ±2–5 seconds/day.
• Spring Drive GMTs (e.g., Grand Seiko): ~±0.5 seconds/day.
• Quartz GMTs: Can be accurate to a few seconds per month or better.

The GMT function itself does not inherently affect accuracy, but high-end GMTs often use precise, chronometer-grade movements.

Best GMT Watches for First-Time Buyers

Let’s get into the fun part: the watches themselves.

Rolex GMT-Master II

The Rolex GMT-Master II is the undisputed icon. Introduced in 1982 as the evolution of the original GMT-Master, it features a 40 mm Oystersteel case, bidirectional Cerachrom bezel in two-tone ceramic, and an independently adjustable hour hand. Inside, it runs on the in-house calibre 3285, a COSC-certified automatic movement with a 70-hour power reserve. Retail starts around €10.500, but most models trade between €12.000 and €18.000 on the secondary market, depending on bezel and condition.

Tudor Black Bay GMT

The Tudor Black Bay GMT is the more toolish, value-driven sibling. The new 39mm fits like the older GMT-Master 40mm from Rolex, snowflake hands, and a matte aluminum “Pepsi” bezel. Its in-house calibre MT5652 offers a 70-hour power reserve and traveler-style GMT function. Wearers love its vintage proportions and tool-watch feel, it’s built to be worn, not babied. Retail starts at around €4.300, but we can get you one between €3.500 to €4.000.

Omega Seamaster Planet Ocean GMT

Need a GMT that can dive 600 meters and still look sharp at dinner? The Omega Seamaster Planet Ocean GMT is your answer. With a 43.5 mm stainless steel case, 600 meters of water resistance, and a black-and-white “panda” dial, it’s built for extremes. It uses the Omega Co-Axial calibre 8906, which is Master Chronometer certified by METAS, and includes a date window and helium escape valve. Retail pricing starts around €7.600, and we can also get you this watch below retail, at around €7.300.

Seiko Prospex GMT

This is one of the best entry-level mechanical GMTs you can buy, period. The Seiko Prospex GMT (with the 6R54 movement) delivers real-world usability at an approachable price. With a 42 mm stainless steel case, 200 meters of water resistance, sapphire crystal, and caller-style GMT functionality, it’s ideal for everyday wear. New models typically sell around €1.400, and they hold their value well on the secondary market.

Quick Comparison

Top GMT Watches by Price and Features

Is It Worth Buying a GMT Watch Pre-Owned?

Absolutely. GMT watches hold value better than most complications, especially from brands like Rolex and Omega. And while many GMT models, especially those from Rolex, tend to trade above retail on the secondary market, buying pre-owned still gives you access to discontinued references, special bezel configurations, and collector-grade condition watches you won't find new. We have a trusted selection of brand new and pre-owned GMTs from verified sellers, complete with transparent pricing, clear photography, and warranty options. It’s a smart way to buy with confidence, whether you're after something iconic or something a little off the radar.

My Take on GMT Watches

I’ll be honest… I don’t actually use the GMT function at all. We’ve got phones, laptops, and world clocks built into everything now, so it's not really about the utility for me. What keeps me interested in GMT watches is the design. There’s something about the bezel colors, like that red and blue “Pepsi” combo that just works. It’s a nice detail with a purpose-driven vibe behind it.

Ready to Explore GMTs?

If you’ve made it this far, you’re clearly interested. Whether you’re hunting for your first GMT or considering an upgrade, take the time to try different styles, movements, and brands. Learn what kind of GMT suits your life, not just your wrist. And if you’re ready to take the next step, explore our full collection of GMT watches.