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What Is a GMT Watch? Meaning, How It Works, and Why It Matters

Emily Smith7 Min ReadJuly 8 2021

A GMT watch, or Greenwich Mean Time watch, features a fourth hand that lets you track two or more time zones simultaneously using a 24-hour format. These timepieces are ideal for travelers, business professionals, and collectors who want a functional and stylish solution for managing international schedules. But what does GMT mean on a watch, and how does it actually work? This guide breaks it all down.

In this article, we’ll break down what “GMT” means, how a GMT watch works, and why it remains one of the most iconic and practical complications in horology.

Zoom InRolex GMT-Master II with dual time zone display and rotating 24-hour bezel

What Does GMT Mean on a Watch?

GMT stands for Greenwich Mean Time, which was established as the standard time at the Prime Meridian (zero degrees longitude) in Greenwich, London. Prior to global time standardization, local solar time was used—leading to inconsistencies, especially in railway and maritime schedules.

In 1884, GMT was officially adopted as the world’s timekeeping standard. Although Coordinated Universal Time (UTC) replaced GMT in 1972 for scientific purposes, GMT remains a common term in the watch world.

Example time zones:

  • Hong Kong: GMT +8
  • Dubai: GMT +4
  • Philadelphia: GMT -5

In watches, GMT originally referred to the second time zone being set to Greenwich Mean Time. Today, most GMT watches allow you to choose any second time zone using the GMT hand and bezel. Some people still refer to GMT time zones as UTC (Coordinated Universal Time), but GMT remains the standard term in horology.

How Does a GMT Watch Work?

The GMT function was popularized in the 1950s when Pan Am asked Rolex to create a timepiece for pilots flying across multiple time zones. The result was the Rolex GMT-Master “Pepsi”, featuring an extra hand on the dial and a 24-hour bezel.

A standard GMT watch includes:

  • A fourth GMT hand that rotates once every 24 hours

  • A 24-hour scale printed on the bezel or dial

  • (Sometimes) an independently adjustable hour hand

This 24-hour GMT hand rotates once per day and is used to track a second time zone. Some modern GMT watches feature independent GMT hands, which allow for even greater functionality, including tracking a third time zone.

Zoom InRolex Sky-Dweller GMT

What Is the Difference Between a GMT Watch and a Dual Time Watch?

A GMT watch uses a 24-hour scale to indicate day/night and track time in two or more zones. A dual time zone watch usually has a second 12-hour dial or sub-dial without a 24-hour reference. If it doesn’t include an AM/PM indicator, it can be harder to know if it’s day or night in the second time zone.

What Does a GMT Watch Do?

A GMT watch allows you to tell the time in multiple time zones by using a 24-hour hand and scale. While your local time is shown by the main hour and minute hands, the GMT hand points to a second time zone. Some watches also allow tracking a third time zone by rotating the bezel.

Using the Bezel

Depending on your watch, the GMT hand may be anchored to the hour hand. As you adjust the local time, the GMT hand will move with it. For the second timezone, you would simply turn the bezel to align with the proper hour. Many GMT watches now have independent hour and GMT hands. This allows you to adjust local time without affecting the GMT hand, ideal for travel. To read a third time zone, rotate the 24-hour bezel accordingly.

Not all GMT watches feature an hour-scale bezel. The Seamaster Aqua Terra GMT, for example, features the 24-hour scale printed between the indices on the dial.

How to Read and Set a GMT Watch

Static GMT Hand

  1. Align the bezel with the 12 o’clock marker.
  2. Set the GMT hand to GMT or your second time zone.
  3. Rotate the bezel to reflect a third time zone, if needed.

Independent GMT Hand (e.g., Rolex GMT-Master II)

  1. Set the GMT hand to your home time (24-hour scale).
  2. Set the local hour hand to your current location.
  3. Rotate the bezel to track a third time zone, using GMT as your anchor.

Note: Watches like the Omega Seamaster Aqua Terra GMT have a fixed 24-hour scale on the dial rather than a rotating bezel.

Zoom InGrand Seiko GMT watch showing 24-hour hand

Using a GMT To Track A Third Timezone

Because many modern GMT functions feature an independent GMT hand, it is possible to track a third timezone by using the GMT hand and 24-hour bezel. To accomplish a third timezone, you will set the GMT hand to current GMT time, and the hour hand set to local time. The bezel can then be rotated to set a third timezone, using GMT as the reference for how many hours to add or subtract, rotate either clockwise or counterclockwise depending on location. The bezel would then align with the third timezone and GMT hand, your local time would be read by the hour hand. It is important to note that the second timezone would need to have the bezel rotated back for reading the time.

Zoom InTudor Black Bay GMT watch with red and blue bezel and fourth GMT hand

Can You Use a GMT Watch as a Compass?

Yes. In the Northern Hemisphere, point the GMT hand at the sun:

  • The 12 o’clock marker on the bezel will then point north.

In the Southern Hemisphere, the reverse applies:

  • Point the GMT hand at the sun, and the 12 o’clock marker points south.

Who Uses a GMT Watch?

GMT watches are ideal for:

  • Pilots
  • Frequent travelers
  • Military personnel
  • Business professionals with global clients
  • Collectors and enthusiasts

It’s also a practical choice for those with family abroad or anyone managing international schedules.

Popular GMT Models

Because of its popularity, the GMT function is found throughout a number of brands and models. Some of the most popular GMT watches include:

Final Thoughts: Why Choose a GMT Watch?

Beyond its heritage and technical innovation, a GMT watch combines style, precision, and utility. Whether you’re navigating different time zones, managing a global team, or simply fascinated by horology, a GMT watch offers a tangible connection to the world.

Not all dual time watches are true GMTs. If a watch lacks a 24-hour hand or AM/PM indicator, it functions differently.

Discover the latest GMT watches at The 1916 Company or shop the entire collection of authorized new watches,  pre-owned luxury watches, or Rolex Certified Pre-owned watches to find your perfect timepiece.

Common GMT Watch Questions

  • Q. What does GMT mean on a watch?
    A. GMT stands for Greenwich Mean Time. On a watch, it refers to a function that allows you to track time in two or more time zones using a 24-hour hand.

  • Q. How do you read a GMT watch?
    A. First, check the local hour hand. Then look at the GMT hand and 24-hour scale or bezel to read the second time zone. If the bezel rotates, align it to read a third zone.

  • Q. What is the point of a GMT watch?
    A. A GMT watch helps travelers, professionals, and collectors keep track of multiple time zones at once—without resetting the watch.

  • Q. What does a 24-hour hand do on a GMT watch?
    A. It tracks a second time zone using a 24-hour scale to indicate AM or PM—something a standard 12-hour hand can’t do.

  • Q. What’s the difference between GMT and dual time watches?
    A. Dual time watches often use a 12-hour subdial and may not include AM/PM indicators. GMT watches use a 24-hour hand, which helps avoid confusion between day and night in different time zones.

  • Q. Can I use a GMT watch to track three time zones?
    A. Yes, if it has a rotating bezel and an independent GMT hand. You set your home time with the GMT hand, local time with the main hour hand, and rotate the bezel to align with a third time zone.