What is a GMT Watch?

What is a GMT watch?

GMT is a complication or function on a watch that displays the time in a second time zone.

A GMT watch typically has an extra (fourth) hand on the dial which is used to indicate the current hour in a different time zone. The GMT function can also be used as a 24 hour hand (aka military time) when set to match the wearer’s local time zone.

“G.M.T.” is an acronym for Greenwich Mean Time. This is the starting point or 0 on the 24-hour international time zone scale (technically midnight).

What is the most popular GMT watch in the world?

That award for the most popular GMT watch in the world would probably go to the Rolex GMT-Master II.

The GMT-Master II is the modern and updated version of the original Rolex GMT-Master, a watch that many say was the first GMT watch ever. It was a collab between Rolex and Pan American Airways in circa 1954.

From a Rolex GMT-Master ad from 1955:

“The GMT-Master watch, whose accuracy is described by Pan Am Pilot-in-Charge Bernard Lorenz as “excellent, well within all navigational tolerances,” is specially designed to tell the time in any two places on earth at once. Two special features – a 24-hour bezel and a special 24-hour hand – make this possible: GMT and local time can be read clearly and simultaneously.

Pan AM Captain C. N. Warren, Jnr., wrote of the GMT-Master used on the non-stop New York to Moscow flight: “The flight itself was navigated by Rolex.” 20 out of 21 airline pilots vote the GMT-Master an indispensable aid. Its special features, plus chronometer accuracy, automatic winding, waterproof case and automatic calendar make it one of the most brilliant contributions to international timekeeping ever invented.”

But while the GMT-Master may have been the first wristwatch with it’s particular execution of the dual time zone complication, and the first to use the term “GMT”, another brand claims to have had the first watch with the ability to track time in multiple zones: the Glycine Airman from 1953 (source).

The Airman was indeed capable of tracking two different time-zones, but it did so by displaying 24 hour time on the dial (rather than 12 hour time we’re all used to) in combination with a 24 hour scale on its rotating bezel.

The original Rolex GMT-Master (ref: 6542) maintained the traditional 12 hour markers on the dial, making it easy to read the time at a glance, but added an additional 24 hour hand. It was powered by Rolex caliber 1036.

GMT Hand:

The GMT hand is traditionally in the shape of an arrow style hand painted in a contrasting color to stand out against the rest of the face and hands.

GMT time isn’t limited to being displayed by an extra hand on an analog watch dial, but this is the most common execution of the dual time zone complication. You may see other creative displays by haute horlogerie independents, but for the purposes of discussing the basics, let’s stick with the common fourth-hand style. Below are some examples…

Rotary Henley with a legible orange GMT hand:

The GMT hand can be long and narrow like the hand on the Invicta Subaqua Noma III GMT:

The GMT hand can also be short like on the Stella Ellis GMT:

Pop Quiz: can you guess which hand is the GMT hand on this Brera Orologi Eterno GMT?

If you guessed the orange hand, you would be correct! This watch has the ISA caliber 8176A with the GMT hand being at the top of the handstack – the blue hand at the bottom of the handstack is an alarm hand. Notice how the orange GMT hand is pointing closest to the 24 hour bezel and the blue hand is pointing to an inner 12 hour scale.

NEXT: True GMT VS Office GMT