What Is a GMT Watch? How the Traveler's Complication Works

If you've ever done the mental math to figure out what time it is back home, a GMT watch was made for you. It's one of the most practical complications in watchmaking, and one of the most popular.

Where the name comes from

GMT stands for Greenwich Mean Time, the time at the Royal Observatory in Greenwich, London, which became the world's reference point for time zones. In the 1950s, as commercial jet travel took off, airline pilots crossing several time zones needed a way to track their home time and their destination's time at once. The GMT watch was the answer, and it has been a traveler's favorite ever since.

How a GMT watch works

A GMT watch looks like a regular three-hand watch with one addition: a fourth hand, often with a contrasting color or an arrow tip. That hand makes one full rotation every 24 hours instead of every 12.

Because it moves at half the speed of the normal hour hand, it points to a 24-hour scale, printed either on the dial or on the bezel. That lets you read a second time zone and tells you instantly whether it's day or night there. That's useful when you're calling someone overseas.

Reading two time zones

1. The regular hour and minute hands show your local time.
2. The GMT hand, read against the 24-hour scale, shows your second time zone, such as home time.

Reading three time zones

Many GMT watches have a rotating 24-hour bezel. Rotate the bezel by the hour difference of a third location, and the GMT hand now reads that third zone off the bezel, while the dial's 24-hour track (if it has one) still shows the second. Three time zones, one watch, no apps.

"Traveler" GMT vs. "office" GMT

Not all GMT watches set the same way, and the difference matters if you travel a lot.

• Traveler (or "true") GMT: the local hour hand jumps independently in one-hour steps. When you land, you move the hour hand to the new local time without stopping the watch or disturbing the GMT hand, which keeps showing home time. This is the most convenient design for frequent flyers.
• Office (or "caller") GMT: the GMT hand is the one that jumps independently. It's ideal if you mostly stay put and want to track a colleague or family member in another zone, but it's slightly less convenient for changing your local time on a trip.

Both are genuinely useful. It just depends on whether you're usually the one traveling or the one staying home.

How to set a GMT watch (general steps)

1. Pull the crown to the time-setting position and set the local time (hours and minutes) as usual.
2. Use the GMT setting position (often the middle crown position) to move the independent hand to your second time zone on the 24-hour scale.
3. If your watch has a rotating bezel, align the bezel to the 24-hour position you want to read.

Always check your specific watch's instructions, as crown positions vary by movement.

Who should buy a GMT?

• Frequent travelers who want home time on their wrist.
• Remote workers and business owners with clients or teams in other time zones.
• Anyone with family abroad who wants to know if it's a good time to call.
• Watch lovers who want a sporty, highly practical complication with a rich aviation history.

The bottom line

A GMT watch earns its place every time you check it. It's a tool watch with real everyday value, and often a colorful two-tone bezel. Have a question about a specific GMT or want help choosing one? Reach out and we'll help. In the meantime, browse our Prestige collection for automatic watches built to travel.