GMT Watch Guide: How It Works and How to Set It

A GMT watch lets you read two or even three time zones at once, using one extra hand and a 24-hour scale. So, if you fly often or work with people abroad, it saves you from mental maths. It is also a very practical choice for Malaysians, because so many of us travel, study or do business across Asia, Europe and beyond.

What does GMT mean on a watch?

GMT stands for Greenwich Mean Time, the time at the Royal Observatory in Greenwich, London. For decades it served as the world's reference time. Today the official reference is UTC, which is almost identical. Still, watchmakers kept the old name. As a result, any watch with an extra 24-hour hand now carries the GMT label. Our watch glossary covers similar terms, such as UTC and dual time.

How a GMT watch works

A GMT watch looks like a normal three-hand watch with one addition. Usually that addition is a slim hand with an arrow tip. In addition, there is a 24-hour scale, either on the bezel or around the dial. Together, they show a second time zone in 24-hour format, so you never confuse 7 am with 7 pm.

The 24-hour hand

The normal hour hand goes round the dial twice a day. The GMT hand, by contrast, goes round only once. Because of this, it points to the correct hour on the 24-hour scale. For example, if the GMT hand points to 20, it is 8 pm in your second zone. Meanwhile, the main hands still show your local time.

The 24-hour bezel

Many models add a rotating 24-hour bezel. Often it has two colours, one for day and one for night. When the bezel sits at its zero position, the GMT hand reads the zone it was set to. However, if you turn the bezel by a few hours, the same hand reads a third zone. In other words, one hand can serve two zones.

True GMT vs office GMT

Not every model sets the same way. On a true GMT, also called a flyer GMT, you pull the crown out one step. Then you jump the local hour hand in one-hour steps, while the watch keeps running. The GMT hand stays on home time, and the date moves with the local hour hand. That is ideal when you land in a new city.

On an office or caller GMT, the reverse happens. You set the 24-hour hand on its own, while the local hour hand moves only with the minutes. So it suits someone who stays put and calls colleagues abroad. Both types tell the time equally well. The difference is simply which hand is easier to change.

Setting a GMT watch: a Kuala Lumpur example

Malaysia uses UTC+8 all year and has no daylight saving. That makes life easy, because your home zone never shifts. Imagine you live in Kuala Lumpur and fly to London in November, when London is on UTC+0. You also want to track Tokyo, which is UTC+9 all year. Here is how you would set a true GMT watch.

1. At home, with the bezel at zero, set the GMT hand to Kuala Lumpur time. At 3 pm, it should point to 15.
2. Set the local hour and minute hands to the same time, 3:00.
3. After landing in London, pull the crown out one step. Then jump the hour hand back eight hours, to 7 am.
4. Leave the GMT hand alone. It still points to 15, so you can see that it is 3 pm at home.
5. Finally, turn the bezel one hour anticlockwise, so the GMT hand now reads 16. That is Tokyo time.

World-timers: every zone at once

If two or three zones are not enough, consider a world-timer. Instead of one extra hand, it has a ring of city names around the dial and a 24-hour disc that turns once a day. So you can read the hour in all the main zones at a glance. However, world-timers are usually more complex and pricier. For most travellers, a simple GMT watch is easier to read and set.

A short history of the GMT watch

The jet age created the need. In the 1950s, long-haul pilots crossed several time zones in one flight. Because of this, Rolex worked with the American airline Pan Am on a watch for its pilots and navigators. The result was the GMT-Master, reference 6542, which arrived in 1954. Its two-colour bezel in red and blue split the day from the night.

Later, in 1982, Rolex launched the GMT-Master II. Its new calibre let you set the hour hand on its own, so it became a true GMT. You can see the current range on the official Rolex site. Since then, many luxury watch brands and affordable makers alike have offered their own versions.

GMT watches across budgets

You do not need a large budget to enjoy one. Here are three verified GMT watch options at different prices. Note that prices change, so always confirm with an official retailer.

• Seiko 5 Sports GMT (SSK001): an automatic watch with the Calibre 4R34, a 42.5 mm case and 100 m water resistance. It works as an office GMT. Seiko Malaysia listed it at RM2,200 at the time of writing.
• Longines HydroConquest GMT: a true GMT in 41 mm or 43 mm, water-resistant to 300 m, with a ceramic bezel insert. The Longines Malaysia site listed it from RM13,750.
• TUDOR Black Bay GMT: a 41 mm steel case, 200 m water resistance and the in-house Calibre MT5652 with a jumping local hour hand.

Is a GMT watch right for you?

If you travel a few times a year, or you work with teams in other countries, the answer is probably yes. Also, a GMT watch is often tough enough for daily wear, since many are built on sports cases. On the other hand, if you rarely leave home, the extra hand may simply add clutter.

It also helps to compare it with other tool watches. For example, a chronograph watch times events, while a diving watch times dives and handles deep water. Some models combine a dive bezel with a GMT hand. Overall, for anyone who lives between time zones, a GMT watch is the most useful travel companion you can wear.