What Is a GMT Watch? How It Works and How to Use One
Why trust this guide? It's written by the Watch Direct team, an authorised Australian watch retailer trading since 2011. Explanations are checked against manufacturers' instructions (including Seiko's calibre 4R34 manual) and respected watch references such as Fratello, Monochrome and Royal Museums Greenwich.
Featured watches were checked for stock and specifications on our store when this guide was written in October 2026.
At a Glance
- A GMT watch shows a second time zone using an extra hand that goes around the dial once every 24 hours.
- Read it against a 24-hour scale on the dial or bezel. A rotating bezel can add a third zone.
- Caller GMTs adjust the 24-hour hand on its own; flyer GMTs jump the local hour hand.
- The name comes from Greenwich Mean Time, the international standard time when the first GMT watches appeared in the 1950s.
In This Guide
What is a GMT watch?
A GMT watch shows the time in two places at once. Alongside the normal hour, minute and seconds hands, it has a fourth hand that makes one full turn every 24 hours. Read against a 24-hour scale, that hand shows a second time zone, such as your home time while you're overseas, or the time where family live.
GMT stands for Greenwich Mean Time, the time at the Prime Meridian in Greenwich, London. For everyday purposes it's the same as UTC (Coordinated Universal Time), the modern standard that time zones are measured from. Sydney, for example, is UTC+10, or UTC+11 during daylight saving.
The idea took off with aviation. Rolex launched its GMT-Master in the 1950s for professionals crossing time zones, and it became the official watch of Pan American World Airways, whose pilots wore it. Rolex notes that Greenwich Mean Time was the international standard time until 1972. Today "GMT" is used for any watch with this kind of 24-hour second-time-zone hand.
How a GMT watch works
- Hour and minute hands show local time, just as on any watch.
- The 24-hour hand, often in a contrasting colour, completes one turn per day.
- A 24-hour scale, printed on the dial or the bezel, numbered 1 to 24 (often in steps of two).
If the 24-hour hand is set to London time and points to 9 on the scale, it's 9 am in London. If it points to 21, it's 9 pm. Because the scale covers 24 hours, the hand also tells you whether it's day or night in that zone, which a normal 12-hour dial can't.
If your watch has a rotating 24-hour bezel, you can track a third zone. Turn the bezel by the time difference to the third city, then read the same 24-hour hand against the bezel instead of the fixed scale.
Caller vs flyer GMT
Not all GMT movements adjust the same way. Watch writers usually describe two types:
Caller GMT
Also called: Office GMT · What you adjust independently: The 24-hour hand · Best for: Tracking another time zone from home
Flyer GMT
Also called: Traveller GMT, "true" GMT · What you adjust independently: The local hour hand, in one-hour jumps (the date follows) · Best for: Frequent travellers changing time zones
| Type | Also called | What you adjust independently | Best for |
|---|---|---|---|
| Caller GMT | Office GMT | The 24-hour hand | Tracking another time zone from home |
| Flyer GMT | Traveller GMT, "true" GMT | The local hour hand, in one-hour jumps (the date follows) | Frequent travellers changing time zones |
Neither type is better. A caller GMT is simpler to set when you mostly stay put, while a flyer GMT lets you change local time on arrival without stopping the watch.
How to set a GMT watch
Steps vary by movement, so always follow your manual. Here's how Seiko's automatic calibre 4R34, a caller-type GMT used in the Presage Cocktail Time GMT, is set:
- Make sure the watch is running. Wind it by turning the crown if it has stopped.
- Set the local time: pull the crown to the second click and turn it to set the time. The hour hand and 24-hour hand move together, so use the 24-hour hand to check you've set am or pm correctly.
- Set the date: push the crown to the first click and turn it anticlockwise. Seiko advises not to change the date when the 24-hour hand is between 9 pm and 1 am.
- Set the second time zone: at the first click, turn the crown clockwise to move the 24-hour hand on its own to the time in your second city.
- Push the crown back in to the normal position.
If you'd rather use the 24-hour hand as an am/pm indicator, simply set it to match your local time.
Using a GMT in Australia
A few practical examples:
- Sydney and Perth: set the 24-hour hand to Perth time. The gap is two hours, or three when Sydney is on daylight saving, because Western Australia doesn't observe it.
- Family overseas: set the 24-hour hand to their city so you know at a glance whether it's a sensible time to call.
- Travelling: set local time on the main hands when you land and leave the 24-hour hand on home time.
Remember that daylight saving changes the gap between cities during the year, so you may need to move the 24-hour hand by an hour in April and October.
GMT vs world time and dual-time watches
- GMT: one extra time zone on a 24-hour hand (two or three with a rotating bezel).
- World timer: the time in all major zones at once, usually with a ring of city names.
- Dual time: a second time display, such as a small sub-dial or a digital readout. Many digital watches, like the Casio AE-1200 or G-Shock models, offer digital world time you scroll through city by city.
GMT watches we recommend
Two very different takes on the GMT. For more, browse our GMT watches or the Seiko 5 range, which includes GMT models.
Seiko Presage · Automatic · Caller GMT
Seiko Presage Cocktail Time GMT SSK049J
A dressy automatic GMT with a textured grey dial, box-shaped Hardlex crystal and an exhibition caseback.
- Calibre: 4R34 automatic with hand-winding
- Power reserve: 41 hours
- Case: 40.5mm stainless steel
- Water resistance: 50m
- Strap: Black leather
Timex · Quartz · GMT window
Timex Continental GMT TW2Y24800
A '70s-inspired Q Timex with a radial green dial, an integrated steel bracelet and a GMT window at 6 o'clock.
- Movement: Quartz
- Case: 39mm stainless steel
- Water resistance: 50m (5 ATM)
- Bracelet: Integrated stainless steel, deployant clasp
Featured watches compared
Automatic (4R34)
Second time zone: 24-hour GMT hand · Case: 40.5mm · Water resistance: 50m
Quartz
Second time zone: GMT window at 6 o'clock · Case: 39mm · Water resistance: 50m
| Movement | Watch | Second time zone | Case | Water resistance |
|---|---|---|---|---|
| Automatic (4R34) | Seiko SSK049J | 24-hour GMT hand | 40.5mm | 50m |
| Quartz | Timex TW2Y24800 | GMT window at 6 o'clock | 39mm | 50m |
Explore GMT and travel watches
Frequently asked questions
What does GMT stand for on a watch?
GMT stands for Greenwich Mean Time, the time at the Prime Meridian in Greenwich, London. On a watch, 'GMT' has come to mean any watch with an extra 24-hour hand that shows a second time zone.
Is GMT the same as UTC?
For everyday purposes, yes. UTC (Coordinated Universal Time) is the modern scientific standard and GMT is the time zone at Greenwich, but they show the same time. Technically, UTC is based on atomic clocks while GMT was based on the Earth's rotation.
What is the difference between a caller GMT and a flyer GMT?
On a caller (or office) GMT, you adjust the 24-hour hand on its own, which is ideal for tracking another city from home. On a flyer (also called traveller or 'true') GMT, you jump the main hour hand in one-hour steps without stopping the watch, which is handy when you land in a new time zone.
Can a GMT watch show three time zones?
Yes, if it has a rotating 24-hour bezel. The main hands show local time, the 24-hour hand against the fixed scale shows a second zone, and turning the bezel by the time difference lets you read a third zone off the same 24-hour hand.
What is the difference between a GMT and a world timer?
A GMT shows one extra time zone with a 24-hour hand. A world timer shows the time in all major time zones at once, usually with a ring of city names around the dial. Digital watches with world time let you scroll through cities on the display.
Is a GMT watch useful if I don't travel?
It can be. Many people use a GMT to keep track of family, friends or colleagues in another time zone, and the 24-hour hand also tells you whether it's day or night, which is useful if you set it to your own time zone.
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