Watch Difference: Dual Time vs GMT

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If you travel frequently or work with people around the globe, a watch that tells more than one timezone at once will be incredibly useful. Just like chronographs and calendars, GMT and Dual Time features are very practical complications.

Both display the time in two timezones at once; but use different mechanisms. So what’s the difference between a Dual Time vs GMT watch? And which one is right for you? Let’s find out.

Dual Time: A Practical Complication

A Dual Time watch is very straightforward. It shows the wearer two different times, at the same time.

Usually, the second timezone is shown on a subdial using a 12-hour time frame. Think of it as a dial within your dial. Sometimes, it can include both hours and minutes, but most often it only shows the hours.

from left: Cartier Drive Steel Chronograph, Rolex Cellini Dual Time Everose Gold Watch, Vacheron Constantin Harmony Dual Time Rose Gold Watch

As it tells time on a 12-hour scale, it often includes a subtle AM-PM indication, so you can tell if its day or night in the second timezone you’re monitoring.

Most people would use a Dual Time while travelling – the main dial to display the local time for the place they are visiting, and the subdial to display their home time zone. This ensures that you’ll never be confused about the time difference again!

GMT Watches: How Do They Work?

Before we go to how GMT watches tell time, let’s discuss a bit of its origin.

The “GMT” stands for Greenwhich Mean Time, which is the starting point on the 24-hour scale of international timezones. Greenwich, which is located in England, is used as the basis of other timezones – from there, each timezone is either ahead or plus (+) GMT, or behind or minus (-) GMT.

The GMT was established so that people around the world can easily tell time in another timezone, as long as they know what the GMT time is.

from left: Omega Seamaster Planet Ocean GMT GoodPlanet Watch, Rolex GMT-Master II Pepsi Bezel Jubilee Steel Watch, Panerai Radiomir GMT Dual Time Watch

Most GMT watches have the traditional hour and minute hand to tell time in the 12-hour format; and then another independently adjustable 24-hour hand, usually in a different color or design that makes it stand out.

In the case of the very popular Rolex GMT-Master, the 24-hour hand is distinguished by its arrow. The second timezone is displayed on the dial or on the bezel, which can either be fixed or rotatable.

If the 24-hour hand cannot be adjusted independently, then it only serves to tell the wearer whether the time is AM or PM.

pictured: Rolex GMT-Master II Pepsi Bezel Jubilee Steel Watch

So how does one read a GMT watch?

Set the bezel at 12 o’clock (in this case, with the arrow at 12). The GMT hand will read the same time as the hour and minute hands.

To tell time in a different timezone, you will need to rotate the bezel depending on how many hours behind or ahead your second timezone is. If the second timezone is a few hours ahead, rotate the bezel. If it’s behind a few hours, retard the bezel.

Use the GMT hand to tell the hour in the second timezone.

Take it up a notch with World Time Watches

Due to advances in travel and technology, it’s now even more commonplace to travel to multiple destinations in one trip; or do business with people around the globe. For that purpose, one should consider getting a World Time watch.

While Dual Time and GMT watches display two timezones at once, a World Time watch gives a quick overview of all 24 timezones worldwide. An outer rotating ring displays cities across the globe that correspond to the 24 timezones.

from left: Vacheron Constantin Overseas Worldtime, Patek Philippe World Time Complications, Jaeger LeCoultre Master World Geographic Watch

So how do you choose the best timer for your needs?

If you tend to travel between two places, like your home and a single city, then a Dual Time or GMT watch may be best for you. The Dual Time is straightforward, showing you two timezones at once, while the GMT requires a little math; and some adjustment.

If you go to multiple destinations in one journey; or work with a global team and need to monitor more than two timezones, then a World Time watch is your best bet.

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