GMT - Keeping Track of Somewhere Else

There was a time when travelling to another time zone took long enough for your watch - and your body - to adjust along the way.

Then came the jet age.

Suddenly you could leave London after dinner and wake up in New York, while the people you had left behind were already starting another day. Distance hadn't changed, but our relationship with time had.

The watch industry responded with one of the most useful complications ever put on a wrist: the GMT.

A GMT watch can tell you the time in two - and, with the right bezel, three - places at once. It was conceived as a professional instrument for pilots crossing continents, but somewhere along the way it became something more.

The GMT became the traveller's watch.

And even in a world where your phone knows the time in Tokyo before you've finished typing the word, I think the GMT remains one of the few watch complications that is genuinely useful.

One of the first GMT watches - the Glycine Airman 

 

How does a GMT work?

The basic idea is remarkably simple.

A conventional watch has an hour hand that completes one rotation of the dial every 12 hours. A GMT adds another hour hand, usually in a contrasting colour or distinctive shape, which makes one complete rotation every 24 hours.

That hand is read against a 24-hour scale rather than the conventional 12-hour dial.

If your normal hour hand shows 3 o'clock, for example, the GMT hand can tell you whether it is 0300 or 1500 somewhere else.

Add a rotating 24-hour bezel and the possibilities become even greater. By offsetting the bezel from the GMT hand, a third time zone can be displayed.

Four hands. One additional scale. Potentially three different places.

Simple, clever and extremely useful.

 

The timezones of the world - a visualisation of the purpose of a watch that shows the time in more than one place at a glance

 

A short history of the GMT watch

The GMT watch is a product of a very particular moment in history.

During the 1950s, long-distance commercial aviation began transforming international travel. Journeys that had previously taken days could suddenly be completed in hours.

That created an entirely new problem.

Pilots could now cross several time zones during a single working day. They needed to know local time, the time at home or at their destination, and the common reference time used for aviation.

 

The original Rolex GMT-Master ref. 6542, introduced in 1955

 

Today we barely think about it. A phone automatically changes time zones the moment it connects to a network. In the 1950s, however, this information had to be calculated and carried with you.

One of the earliest purpose-built watches to tackle the problem was the Glycine Airman.

Introduced in the early 1950s, the Airman used a 24-hour dial and a rotating 24-hour bezel. The bezel could be locked in position using a second crown at 4 o'clock, allowing another time zone to be referenced.

It was an ingenious piece of functional watchmaking and became particularly popular with pilots.

But if Glycine helped establish the idea, Rolex turned it into an icon.

In 1954, Rolex introduced the GMT-Master following a request associated with Pan American World Airways - Pan Am - one of the great pioneers of international commercial aviation.

The GMT-Master took a slightly different approach.

Instead of using a 24-hour primary display, it retained the familiar 12-hour hour hand and added a separate 24-hour hand. Around the outside sat a bi-directional 24-hour bezel.

It was intuitive, colourful and immediately recognisable.

And unlike many professional watches, it quickly escaped the profession for which it had originally been created.

The GMT-Master became associated not merely with pilots, but with travel itself - airports, long-haul flights, foreign cities and the emerging jet-set lifestyle.

Few watches have been more successful at turning a practical function into an identity.

Today, virtually every major watch manufacturer offers some interpretation of the GMT.

 

The Rolex GMT-Master Pepsi, reference 126710BLRO. One of the most sought-after sports watches from the Swiss giant

 

GMT, UTC - and why the name stuck

To understand the original purpose of the GMT watch, it helps to understand GMT itself.

Greenwich Mean Time takes its reference from the Greenwich meridian at 0° longitude in London. For generations it provided the basis from which the world's time zones were calculated.

Today, the international reference is Coordinated Universal Time - UTC.

The abbreviation is slightly peculiar. The English expression would logically produce CUT, while the French Temps Universel Coordonné would produce TUC. UTC was adopted as a compromise that favoured neither language.

UTC does not observe daylight saving time. It remains constant regardless of where you happen to be in the world, which makes it particularly useful in aviation and other activities where ambiguity about time would be undesirable.

The aviation world therefore operates using UTC.

So why do we still call these watches GMT watches?

Mostly because the name had already stuck.

GMT had become part of the language of navigation and international travel long before UTC became the modern standard. And, frankly, "UTC watch" never had quite the same ring to it.

Two GMT watches that look the same - but aren't

This is where GMT watches become particularly interesting.

There are two principal ways of constructing a modern GMT movement. From the outside they can look virtually identical. You generally won't know which type you are wearing until you pull out the crown and try to adjust it.

They are normally described as the Traveller GMT and the Caller GMT, the latter also commonly known as an Office GMT.

The simplest way of remembering the difference is this:

Traveller GMT: I am moving; home stays where it is.

Caller GMT: I am staying here; I want to know what time it is somewhere else.

Neither concept is inherently right or wrong. They simply approach the same problem from opposite directions.

The Traveller GMT

As the name suggests, the Traveller GMT - also called a Flyer GMT - is the most convenient solution for someone who regularly crosses time zones.

The watch displays conventional local time using the central hour and minute hands. A separate 24-hour hand can then be used to retain a reference to home time, UTC or another chosen location.

The clever bit happens when you arrive somewhere.

On a Traveller GMT, the conventional 12-hour hand can be moved independently forwards or backwards in one-hour increments without stopping the watch or disturbing the GMT hand.

Let's take an actual journey.

Assume you are in London and board a flight to New York at 9pm on January 6th.

Before departure, your conventional hour hand shows 9pm. Your GMT hand points to 21 on the 24-hour scale. The date shows January 6th.

Both are therefore showing London time.

Six hours later you arrive in New York.

Your watch now reads 3am on January 7th - which is correct in London - but New York is five hours behind London at that time of year.

So you pull out the crown and move only the conventional hour hand backwards by five one-hour jumps.

3am becomes 2am, then 1am, midnight, 11pm and finally 10pm.

And here is the particularly clever part.

As the hour hand crosses midnight backwards, the date changes with it. January 7th becomes January 6th again.

Your watch now tells you everything you need to know.

The normal hour and minute hands show 10pm - local New York time.

The date correctly shows January 6th.

The GMT hand remains untouched at 3am - London time.

The movement has effectively allowed you to move yourself to New York while leaving home exactly where it was.

That is the beauty of a Traveller GMT.

Historically, this type of functionality tended to be associated with comparatively expensive watches. More recently, movements such as the Miyota 9075 have brought true Traveller GMT functionality into much more accessible territory.

The Caller GMT

The Caller GMT approaches the problem from the opposite direction.

Here, the conventional hour hand remains part of the normal timekeeping mechanism. Instead, it is the 24-hour GMT hand that can be independently adjusted.

Imagine that you live in London and regularly deal with colleagues or customers in San Francisco.

It is 12 noon in London.

San Francisco is eight hours behind, so it is 4am there.

Your normal hands remain at 12 noon. You simply adjust the GMT hand until it indicates 0400 hours on the 24-hour scale.

At a glance you can now see both times.

But we can go one step further.

Perhaps you also regularly speak to someone in New York, three hours ahead of San Francisco.

Rotate the 24-hour bezel anti-clockwise by three hours and the GMT hand can now be referenced against two different scales.

You have London on the conventional hands, San Francisco on the fixed 24-hour scale and New York on the bezel.

Three cities. One watch.

When travelling with a Caller GMT, you have a choice. You can leave the conventional hands showing home time and adjust the GMT hand to the place you are visiting, or you can reset the entire watch to local time if you are staying for longer.

It isn't quite as effortless as the jumping local-hour system of a Traveller GMT, but it works perfectly well.

There is a tendency among watch enthusiasts to describe the Traveller as the "true" GMT and the Caller as somehow being a lesser version.

I think that's slightly unfair.

They were simply designed to solve two different problems.

If you regularly step off aeroplanes into different time zones, the Traveller GMT is unquestionably the more elegant solution.

If you spend most of your time in one place but regularly communicate with people elsewhere in the world, the Caller GMT arguably makes just as much sense.

Popular Caller GMT movements include the ETA 2893-2, Sellita SW330 series and Seiko NH34. The Miyota 9075 takes the alternative Traveller approach.

And from the front of the watch, you may never know the difference.

 

The Enoksen Roam E07/A GMT. The Roam was our first GMT watch and was based on the Seiko NH34 Caller GMT movement

 

So which GMT should you choose?

In a perfect world, I would choose the Traveller.

Being able to jump the local hour hand forwards and backwards without stopping the watch is simply a beautifully elegant piece of engineering. Arrive somewhere, move the hour hand, and carry on.

But it isn't essential.

Both types allow you to see two time zones simultaneously, and with a rotating 24-hour bezel both can potentially show three.

The real question is therefore not which system is "proper".

It is what you actually want the watch to do.

But do you actually need a GMT watch?

Objectively? Probably not. Your phone is considerably better at this.

Your phone is also a more accurate stopwatch than a mechanical chronograph. It contains a better compass than most adventure watches. It will tell you the date, the altitude, sunrise and sunset, the weather in Singapore and precisely what time it is in Auckland.

That's not really the point. A GMT puts another place on your wrist.

Perhaps it is where you do business. Perhaps it is where your family lives. Perhaps your daughter is studying abroad. Perhaps your partner is travelling. Perhaps it is simply the place you are going next.

There is something rather satisfying about looking at your wrist and knowing, without reaching for a screen, that it is 7.15 in New York, midnight in London or already tomorrow morning in Tokyo.

The GMT complication isn't really about knowing what time it is.

It is about knowing what time it is somewhere else.

And that is a subtle but rather beautiful distinction.

Enoksen and the GMT

We introduced our first Enoksen GMT at the beginning of 2023.

We had wanted to make one for years, but the movement had always been the stumbling block. We needed something automatic, reliable, serviceable, made by a manufacturer we trusted - and available at a price that would allow us to make the watch accessible.

Then Seiko introduced the NH34 and the problem was solved.

The NH34 belongs to the same movement family as the NH35, which we had already used extensively since the early days of Enoksen. We knew the architecture, knew how dependable it could be and knew that it could be regulated and serviced without drama.

For me, that matters.

There is very little romance in making a watch that becomes somebody else's problem five years later.

Our first GMT became the Roam E07/A.

We based it on the 40.8mm case architecture already used for the Dive E02. That gave the Roam something slightly unusual for a travel watch: the toughness and water resistance of a serious dive watch.

It has 300 metres of water resistance and an anti-reflective sapphire crystal.

But one of the details I cared most about was much smaller. The bezel. A surprising number of affordable GMT watches use what is essentially a diving bezel mechanism underneath a 24-hour scale - 60, 90 or 120 clicks, and sometimes even uni-directional.

It works.

But it has always struck me as a slightly lazy solution.

A GMT bezel represents 24 hours. To me, 24 positive clicks - one for every hour - simply makes sense. And because travelling east is every bit as legitimate as travelling west, it should obviously rotate in both directions.

So the Roam received a bi-directional 24-click ceramic bezel.

Click. One hour. Click. Another hour. Exactly as it should be.

These are tiny details. Most people will never buy a watch because of them.

But they are exactly the sort of details that matter when you are making one.

The Roam E07/A was offered on our vulcanised Tropic rubber strap or a tapered Oyster-style steel bracelet. It wasn't intended to be a copy of the classic GMT-Master formula. It was our interpretation of what an everyday GMT could be: useful enough for travelling, tough enough for almost anything else.

In 2025, the Roam E07/B followed.

The underlying idea remained the same, but the personality changed. It was another interpretation of the GMT - a little more classic in some respects, but still unmistakably part of the Roam family.

And I suspect it won't be our last.

The Enoksen Roam E07/B GMT. A limited edition which is mechanically identical to the E07/A

 

Somewhere else

Perhaps that is why I have always liked GMT watches.

They belong to a particular tradition of watchmaking in which a complication existed because somebody actually needed it.

Divers needed to know how long they had been underwater.

Racing drivers needed to measure elapsed time.

Pilots needed to know what time it was somewhere else.

Today, most of us need none of those things from a watch.

And yet the GMT has somehow become more relevant rather than less.

We travel. We work internationally. Our families live in different countries. We buy from people on the other side of the world and speak to friends thousands of miles away.

Our lives increasingly exist in more than one place.

Perhaps you don't need a GMT watch.

But if part of your life is somewhere other than where you happen to be standing, it is rather nice to have that place on your wrist.