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World timers versus GMT watches – what’s the difference?

World timers versus GMT watches – what’s the difference?

Jamie Weiss

These days, keeping track of the time as you cross the globe and enter different time zones has never been easier. If you’ve got a phone or a smartwatch (or a GPS quartz watch), as soon as you arrive in a new time zone, you’ll connect to the local cellular network and your device will update to the correct local time instantly. But timekeeping while travelling has not traditionally been this easy – making travel watches, or watches that can track time in multiple locations or time zones, utterly essential accessories for frequent travellers. Generally speaking, when it comes to mechanical watches, there are two main types of travel watches: world timers and GMT watches. Similar but not the same, they’re frequently confused with each other – however both operate in crucially different fashions. Here’s a simplifier breaking down the differences between the two.

A quick history

dual time pocket watch
A 19th-century Bourdin dual time pocket watch, restored by Parmigiani Fleurier. Image courtesy of the Maurice-Yves Sandoz Collection

Dual time watches – that is, watches that can tell two sets of time – have existed since the 19th century, with the Industrial Revolution, colonisation, and globalisation making it increasingly important to be able to conveniently track time in two different locations across the world. Early dual time watches accomplished this by simply putting two movements or clockworks into one timepiece that could be set to different times – a method that continues to see sporadic use even today. However, it’s not necessarily what you’d call the neatest solution.

dual time world time
L-R: a Vacheron Constantin Prestige Dual Time from 1978, and a Patek Philippe ref. 515 Heure Universelle from 1931.

Back in the late 1800s, Swiss watchmaker Emmanuel Cottier tackled a challenge posed by the Canadian Railway: tracking time across multiple time zones during cross-country journeys. Although Cottier’s initial attempt fell short, his son Louis – also a prize-winning watchmaker – turned the idea into reality in 1931 with the “heures universelles” complication. It featured a rotating 24-hour ring displaying various time zones, framed with different locations across different time zones.

Patek Philippe Complications World Time Date 5330G WW24
The Patek Philippe Complications World Time Date 5330G is a contemporary example of a Patek world timer.

Patek Philippe went on to commission Louis Cottier to create the brand’s first world timer wristwatch, the reference 515, and thus the problem was solved. Other brands followed suit, producing their own world timers with Cottier’s input. To this day, world timers remain somewhat of a signature for Patek, and world timers are generally considered a prestigious complication.

Longines dual time watch 1925
A Longines Zulu Time from 1925.

These days, however, the GMT watch is the most popular type of mechanical travel watch. We have Rolex to thank for that, with both the formula and the term gaining popularity thanks to its GMT-Master. To be clear, Rolex didn’t invent the concept of using a second centrally mounted hour hand to track another time zone – Longines had the Zulu Time in 1925 and Glycine had the Airman in 1953 – but it’s undeniable that the GMT-Master has defined the format.

rolex gmt master 6542
The Rolex GMT-Master ref. 6542, the originator of the ‘GMT watch’ moniker. Image courtesy of Bob’s Watches

The GMT-Master owes its genesis to the now-defunct American airline Pan Am, who in 1954 commissioned the watch from Rolex for their pilots: since pilots constantly travel between multiple time zones, they needed a watch that could display their time at home (or a reference time, such as UTC/GMT) and be easily set to a new local time when they landed, without disturbing the home time displayed. The GMT-Master remains one of the most influential and popular Rolexes ever, with its original bicolour “Pepsi” bezel colour scheme (the red and blue actually chosen to reflect Pan Am corporate colours) itself format-defining.

So what are the main differences between world timers and GMT watches?

chopard luc time traveller one
The Chopard L.U.C Time Traveller One Black combines a contemporary monochromatic colour scheme with a traditional world timer layout.

Generally speaking, world timers use rotating city or 24-hour discs or rings to track multiple time zones, whilst GMT watches use a second hour hand. It’s also fair to say that listing cities or locations rather than using 24-hour scales or the like is also a defining feature of world timers. However, where things can get confusing is when these two different formats intermingle.

Mido Ocean Star Decompression Worldtimer bezel
The Mido Ocean Star Decompression Worldtimer has features of both GMT watches and world timers.

Take for instance the Mido Ocean Star Decompression Worldtimer. This watch features a second hour hand, a fixed 24-hour ring on its dial (as well as multi-coloured decompression timing rings, but just ignore those for a second) as well as a bidirectional world time bezel. We tend to associate rotating bezels as being a characteristic of GMT watches, and its ETA C07.661 movement is a GMT movement – effectively, it’s a GMT watch masquerading as a world timer, or if we’re being more generous, it’s a novel and affordable execution of a world timer.

RADO CAPTAIN COOK OVER POLE
The Rado Captain Cook Over-Pole is an example of a dive watch that’s been turned into a ‘world timer’.

Indeed, it’s become somewhat common for affordable watchmakers to take dive watches and swap out their unidirectional diving bezels for bidirectional bezels with city markings and marketing them as world timers. Is this deceptive or wrong? Not really, although I think many collectors would not consider these types of watches to be true world timers. It’s not a very technical explanation but sometimes the difference between GMTs and world timers is simply down to aesthetics, or even more prosaicly, the vibe.

nomos glashutte tangomat gmt
The minimalist Nomos Tangomat GMT isn’t your typical GMT watch and in some ways could be better described as a world timer.

Things get even more confusing with watches like the Nomos Tangomat GMT. Again, it’s described as a GMT watch, yet it doesn’t feature a second hour hand. Instead, it features a window at 9 o’clock with 24 different airport codes to denote different cities/time zones – a design choice that feels more world-timer-y (again, it’s the vibe!) – plus a 24-hour indicator at 3 o’clock which takes the place of a GMT hand, and resembles a date window. This is all to say that in modern watchmaking, the distinctions between these two main types of travel watches are often quite blurred.

Can they be one and the same?

Raymond Weil Freelancer Worldtimer GMT
The Raymond Weil Freelancer Worldtimer GMT could rightfully be described as being both a GMT and a world timer.

Confusingly, they can be – although that’s a less common format. Some world timers feature second hour hands like GMT watches as well as rotating 24-hour rings or city rings, allowing the wearer to track up to three time zones simultaneously. Some examples of world timers that feature this functionality include the Alpina Startimer Pilot Quartz World Timer and Raymond Weil Freelancer Worldtimer GMT.

Zodiac World Time Black Dial Still
Even if it didn’t have its world time bezel, you’d still be able to use this Zodiac Super Sea Wolf World Time as a GMT watch thanks to its second hour hand and dial-mounted 24-hour ring.

You could also describe some of the GMT watches-come-world timers discussed earlier in this article as belonging to both camps. For instance, the Mido Ocean Star Decompression Worldtimer mentioned earlier in this article would still function as a GMT watch even if you got rid of its city-denoting bezel, as would other watches that execute a ‘world timer’ complication in this fashion.

SEAMASTER AQUA TERRA 150M WORLDTIMER SUMMER BLUE
The Omega Seamaster Aqua Terra 150M Worldtimer GMT’s name is a bit of a misnomer.

Even more confusingly, there are some watches that describe themselves as being both world timers and GMTs when they’re really just one or the other. For example, the Omega Seamaster Aqua Terra 150M Worldtimer GMT has both those descriptors in its name, and while its Calibre 8938’s independently adjustable hour hand is certainly evocative of a GMT movement, the lack of a second hour hand means this watch is probably best described as ‘simply’ a worldtimer.

Bovet Dimier Recital 27 Dial 2
The Bovet Dimier Récital 27 eludes simple categorisation.

Other watches go beyond these simple definitions. Take the Bovet Dimier Récital 27, which has two main central hands that tell a reference time like a GMT watch, two subdials with their own hour and minute hands like a traditional dual time watch, and two city rings that evoke world timers. Of course, this is an extreme example, but you get my point.

Casio G Shock Mudman GW 9500 black dial
Among myriad other complications, this Casio G-Shock Mudman GW-9500 has a world time function with 48 different cities… But does that make it a world timer?

On a less highfalutin level, many digital quartz watches are described as having world time functions, as they can track multiple time zones and usually offer an easily accessible UTC/GMT mode, but can digital watches really be called world timers? Does a world timer or GMT watch necessarily have to be an analogue watch? Like many categories or definitions in horology, things are complicated. Pun not intended.