What [in the world] is a GMT?

GMT, also known as Greenwich Meridian Time or Greenwich Mean Time, is the basis from which every time zone in the world sets the time of day. In other words, Greenwich is the “mean time” against which the rest of the world’s time zones are compared. Thus, the time in any location can be calculated by simply knowing the time in Greenwich, England and adding or subtracting hours from that time, based on time zone. This simple calculation allows travelers to pinpoint the exact time at any given place on the planet.

Greenwhich Mean Time


What is a GMT?

When the first jets began making their way around the world in the early 1950s, they created intriguing challenges. Pilots needed a device that could tell the time in their current location as well as the time in their destination. Thus, the GMT watch was born. Rolex developed their first GMT timepiece for Pan Am in 1954—the GMT-Master. For a brand associated with adventure and new exploration, it was a perfect match.

What is a GMT?: Rolex GMT-Master

The Rolex GMT-MAster ref. 1675

The world’s first GMT-Master, the ref. 6542, had a novel way to tell the time in two different locations at once. The now-iconic “Pepsi” watch had a dual red-and-blue color scheme, a rotating 24-hour bezel, and a red 24-hour hand. While many GMT watches made today are made by other brands, the GMT-Master was a unique and advanced technological innovation in its time.

What is a GMT?

Several iterations of the 24-hour GMT display

Since their creation, GMT watches have risen in popularity not only for their functionality but also for their aesthetic appeal.  Undoubtedly, the GMT watch has evolved greatly over the years, varying in its look as well as function. They have also remained very relevant today due to the increased globalization. And while they may not be as visually arresting as world timer watches, plenty of companies have made the GMT function all their own.


How to Spot a GMT Watch

Despite the many takes on this type of timepiece, there are a few features that remain consistent among true GMT watches:

  1. A second, minute, and independent 12-hour hand that displays AM and PM
  2. One 24-hour hand that displays the time in Greenwich, England
  3. A bi-directional rotating 24-hour bezel
  4. A setting crown with three positions

While smartphones have technically ousted the need for a GMT watch, it remains a more handsome and personal companion on any journey. Whether you’re trekking across the globe or just your daily commute, consider a GMT watch to wear on your journey.


Editor’s Note: This article was originally published on May 15, 2015. We have updated it for clarity.

Image Credits: Header,2-3; Crown & Caliber. 1; World Time Zone.

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Latest comments
  • nO OFFENSe but this is extremely poor journalism on your part. glycine was the first to release a g.m.t. watch in 1953, their airman model. also, for some reason, the website is not letting me type in lowercase?

    • Hi Karan, we are referring to the first GMT that Rolex made. Hope that clears up confusion.