A GMT watch lets you check the time in two different places. You can see the time where you are while keeping track of the time at home, where a family member lives, or where a team you work with is based.

In the typical analog design, that second time is shown by an additional hand and a 24-hour scale. Let’s look at how to read it and the differences you’ll find when adjusting different models.

A Hand That Goes Around Once a Day

The familiar hour hand makes two full rotations each day. In a typical GMT design, the additional hand makes just one rotation in 24 hours and is read against a 24-hour scale.

It usually stands out through its color, shape, or arrow-shaped tip. The corresponding scale may be on the dial, around its edge, or on the bezel, the ring surrounding the crystal.

That full rotation lets you distinguish morning from evening: 8 means eight in the morning, while 20 means eight in the evening. The 24, or 0 depending on the design, marks midnight.

To read the minutes, you use the regular minute hand. Later, we’ll look at a detail worth checking if the time zone you want to follow has a half-hour offset.

It’s Ten Here and Four Back Home

Imagine you’re somewhere that is six hours behind home. We’ll treat that difference as fixed for this example.

The main hands show 10:10 in the morning. The GMT hand, which you’ve left tracking the time at home, points slightly past 16 on its scale. The minute hand shows ten minutes past the hour.

At home, it’s 16:10, or 4:10 in the afternoon.

Although both hour hands share the same dial, you need to read each one against its own scale: local time on the familiar 12-hour scale and GMT time on the 24-hour scale.

The fourth hand lets you keep another place in mind without losing track of the time where you are.

What Does GMT Mean?

GMT stands for Greenwich Mean Time, a historical reference used to express time differences.

In watchmaking, the term refers to this function for tracking another time zone. The additional hand can show the time at home, where a family member lives, or at an office you work with. You don’t have to keep it set to Greenwich time.

There’s a practical point to remember: a traditional mechanical GMT doesn’t know when a city switches to daylight saving time. If the time difference between the two places changes, you’ll need to adjust the setting.

Two Ways to Adjust a GMT

When comparing models, you’ll come across terms such as caller, office, flyer, or traveler. They describe a useful difference in the mechanism: which hand you can adjust independently.

On a caller or office GMT, you can adjust the 24-hour hand separately. This is convenient when you keep your usual local time and want to change the place whose time you’re tracking.

On a flyer or traveler GMT, you can adjust the local hour hand separately, usually in one-hour increments. When you arrive at another destination, you change that hand while the GMT hand continues to show your reference time.

Both let you track two time zones. The difference is in how you use them: if you travel frequently, adjusting local time can be especially practical; if you check the time in other places from home, adjusting the GMT hand directly can work very well.

What a Rotating Bezel Adds

Some GMT watches have a rotating bezel with a 24-hour scale. By moving that scale relative to the GMT hand, you can check another time zone without readjusting the movement.

This is what makes it possible to check a third time zone, but it’s worth looking closely at the specific design.

If the watch also has a fixed 24-hour scale, you can read the second time zone on that scale and the third on the bezel. If the only 24-hour scale is on the bezel, rotating it changes the reference you’re reading. That’s why you shouldn’t assume that all GMT watches display three time zones simultaneously in the same way.

There are also GMT watches with a fixed bezel or no outer scale. The basic function still comes from the 24-hour hand.

Useful Even When You Stay Home

A GMT can be useful if you work with a team in another country, have family far away, or follow events in another time zone.

Before choosing one, think about which time you want to check and how often you’ll be changing locations. Then make sure you can easily distinguish the GMT hand and read the 24-hour scale. That clarity matters every time you look at the watch.

One more detail: some time zones have half-hour or 45-minute offsets. If you need to track one of them, check how the model you’re considering can display it. Not all systems offer the same possibilities.

Before You Turn the Crown

The setting procedure and calendar precautions depend on the movement. Check your model’s manual before changing the time or date; the instructions for one GMT don’t necessarily apply to another.

Once it’s set, keep this idea in mind: the main hands tell you the time where you are, and the fourth hand helps you know the time in that other place that matters to you.