In a world where work, relationships and travel often stretch across the country or around the globe, keeping track of different time zones isn’t just convenient—it’s essential. Meet the GMT watch, designed to display a second time zone based on “Greenwich Mean Time,” the time at the Prime Meridian (zero degrees longitude), which runs through Greenwich, England. Greenwich was selected as the global standard for timekeeping in 1884, a decision that still influences how we track time today.
How a GMT watch works
Unlike a traditional three-hand watch (hour, minute and seconds), a standard GMT watch features a fourth hand known as the GMT hand, often marked by a small arrow or triangle in blue or red. This hand makes one complete rotation every 24 hours (compared to the regular hour hand which circles the dial twice a day) and points to a second time zone, typically tracked on a rotating 24-hour bezel or a 24-hour scale on the dial.
This dual-time display makes the GMT watch a favorite among frequent fliers, remote workers with cross-continental colleagues, clients, or anyone with loved ones far away. Whether you're a casual watch enthusiast or a seasoned aficionado, a GMT watch offers practical functionality and effortless style. Let’s explore GMT watches, from how they work to their iconic history to how to use one like a pro.
The history of GMT watches
The use of the Greenwich Mean Time dates back to the 1600s when the Royal Observatory was established in Greenwich to improve navigation for sailors and assist mapmakers in charting longitude. 1884, during the International Meridian Conference, 25 countries voted to make GMT the global timekeeping standard* – the baseline from which all other time zones would be calculated.
*UTC (Universal Time Coordinated, more commonly referred to as Coordinated Universal time) is the current timekeeping standard, but it’s often used interchangeably with GMT.
The GMT offset formula:
To calculate the local time of a second time zone, countries used the global timekeeping standard and simply added or subtracted a number of hours.
Local Time = GMT +/- (number of hours)
Here are a few examples:
Tokyo: GMT+9 (Tokyo is 9 hours ahead of GMT)
New York: GMT-4 (New York EDT is 4 hours behind GMT).
Los Angeles: GMT-7 (Los Angeles is 7 hours behind GMT).
London: GMT+0 (This is ground zero or the starting point for GMT since Greenwich is an area in Southeast London).
While Greenwich Mean Time originated at sea, GMT watches were born in the skies. As commercial air travel took off in the 1950s, pilots and airline crews, particularly those flying transatlantic routes, needed a dependable way to track both their home base and local destination times. To meet this growing demand, Pan Am Airlines commissioned Rolex to develop a watch that could help flight crews easily navigate global routes. This groundbreaking timepiece was equipped with a fourth GMT hand, enabling aviation personnel to instantly reference two time zones at a glance from 35,000 feet.
Today, GMT watches are as popular as ever, prized for their old-world charm, mechanical ingenuity, practical utility and all-around cool factor.
How to use a GMT watch: traveler GMT vs caller GMT
If you’re tempted to add a GMT timepiece to your collection, there are two main types of GMT watches on the market: the Traveler GMT (also known as the Flyer GMT or True GMT) and the Caller GMT (or Office GMT). Let’s take a closer look at which one might be right for you and how to use it.
Traveler GMT watch
Ideal for: Jetsetters, globetrotters, business executives and anyone who frequently switches time zones.
Key feature: Lets you independently adjust the local hour hand forward or backward to a new time zone while the GMT hand remains fixed to your home time.
How to use a traveler GMT Watch
Example scenario: You live in New York (Eastern Time) and are flying to London (GMT). The main hand will show the local time in London, and the GMT hand will show your home time in NY.
Steps:
- Set your home time using the GMT hand. Unscrew the crown and pull it out to the second position – this lets you set the minute hand and GMT hand together. Use the 24-hour bezel or scale to align the GMT hand with your home time. For example, if it’s 9:00 AM in New York, set the GMT hand to 09.
- Set the local time in London by pushing the crown to the first position. This lets you jump the local hand forward to match London time, five hours ahead of New York. So, if it’s 9:00 AM in New York, it’s 2:00 PM in London.
- Adjust the date (if applicable). If your GMT watch has a date window, check if the date needs adjusting after setting the time. To change it, pull the crown to the first position and turn it until the correct date appears (direction may vary depending on the model).
PLEASE NOTE: Avoid changing it between 8 PM and 4 AM – this is when the watch gears change automatically and forcing it can cause damage.
Bonus tip: If your GMT watch has a rotating bezel, you can track a third time zone if you wish. How about Dubai? Using the time zones from the example above, Dubai is 9 hours ahead (GMT + 9) of New York’s home time. To set this, you would rotate the 24-hour bezel nine clicks clockwise so that it now reads 6:00 PM (local Dubai time) or 18:00 on the bezel. Your watch will now display at 9:00 AM in NY, 2:00 PM in London, and 6:00 PM in Dubai. How cool is it to be in three places at once?
Office GMT watch
Ideal for: Someone who stays in one place but has colleagues, clients, or family and friends in a different time zone.
Key feature: Allows you to move the GMT hand to a second time zone without affecting your main local time display.
How to use an office GMT watch
Example scenario: You live in Los Angeles (Pacific Time) and work with a team in Tokyo (Japan Standard Time). The main hand will show your home time in Los Angeles, while the GMT hand will show time in Tokyo.
Steps:
- Set your home time. Pull the crown out to the second position and set the main hour and minute hands to your local time – let’s say 11:00 AM in Los Angeles.
- Set the GMT hand to your second time zone. Push the crown to the first position and rotate the GMT hand to match Tokyo time. Tokyo is 16 hours ahead of Los Angeles, so if it’s 11:00 AM in Los Angeles, set the GMT hand to point to 3:00 AM the next day on the 24-hour scale for Tokyo time.
- Set the date (if applicable). If your watch has a date window, rotate the crown counterclockwise to adjust it. The date is usually tied to the local time, so you may need to move the hour hand past midnight to trigger a date change.
PLEASE NOTE: Avoid changing it between 8 PM and 4 AM – this is when the watch gears change automatically, and forcing it can cause damage.
Insuring your GMT watch
Whether you're getting a GMT watch for travel, managing time zones, staying connected with loved ones, or embarking on new adventures, be sure to properly care for and insure it. Obtaining personal jewelry insurance through Jewelers Mutual is affordable and covers loss, damage, and disappearance. You can check your rate by clicking the button below.
