GMT Watch Timezone Calculator

Calculate and convert timezones with your GMT watch. Use the dual timezone, world time, and UTC offset tools below.

Dual Timezone Converter

Convert time between two timezones as displayed on a GMT watch.

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World Time Calculator

See the time across multiple major cities as displayed on a world timer watch.

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GMT Bezel Timezone Converter

Calculate the bezel position and GMT hand position for your desired timezone.

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Formula

Target Time = Local Time + (Target UTC Offset - Local UTC Offset) | GMT Hand Position = UTC Time (mod 24) | Bezel Rotation = Target Offset - Home Offset hours

Frequently Asked Questions

How does a GMT watch work?
A GMT watch has an additional 24-hour hand paired with a 24-hour bezel. The GMT hand shows a second timezone. On a "true GMT," the local hour hand can be independently adjusted while the GMT hand stays on home time.
What is the difference between a GMT and a World Timer?
A GMT shows two timezones using a 24-hour hand. A World Timer shows all 24 timezones at once using a rotating city disc and 24-hour ring. World Timers let you read time in any major city at a glance.
How do I set a GMT watch for travel?
For a true GMT: Set the GMT hand to home time using the 24-hour bezel, then jump the local hour hand to destination time. For a caller GMT: Keep the main dial on local time and adjust the GMT hand for the second timezone.

Understanding GMT Watches

The GMT complication was developed for Pan Am pilots in the 1950s, resulting in the iconic Rolex GMT-Master. Today, GMT watches are essential tools for travelers, international business professionals, and anyone who needs to track multiple timezones.

Types of GMT Watches

True GMT (Flyer/Traveler): The local hour hand can be independently set in 1-hour jumps without stopping the movement. The GMT hand tracks home time continuously. Found in the Rolex GMT-Master II, Grand Seiko SBGJ, and Omega Seamaster Aqua Terra GMT.

Caller GMT (Office): The GMT hand can be independently set. The main dial shows local time permanently. Better for staying in one timezone and tracking a remote one. Found in the Tudor Black Bay GMT and many ETA 2893-based watches.

World Timer: Shows all 24 timezones simultaneously with a rotating city ring. Found in the Patek Philippe 5230, Vacheron Constantin Overseas World Time, and Jaeger-LeCoultre Geophysic Universal Time.

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