This is the ultimate How to Use a GMT Function Guide! Whether you are a beginner or a pro, we walk you through every step of how to properly set a GMT Function for 3 time zones.
One of the most popular watches out there right now has got to be the Rolex GMT Master II with its two-tone bezel. We love the combinations customers have created with the Everest Bands and their GMT Master II's. To see some of these gorgeous combos, make sure you check out our Shop Instagram section at the bottom of this strap page. The GMT Master 2 is a gorgeous watch...but...do you really know how to use its GMT function?
I’m going to show you the abilities of your GMT watch, how to get the most out of it, and some basics about time while traveling. Grab your watch and have a seat. Let’s get started.
Before we even get to the watch itself, you need to understand the concept of 24 hour time (otherwise known as Military Time) and time zones. We’re all aware that each day is comprised of 24 hours and that we all live in one of 24 time zones (24 hours in a day = 24 time zones around the world).
Currently, where I am in St. Louis, Missouri, in the U.S., it’s 10:10am here in the Central Time Zone. That’s easy to set on your watch, but in order to use the GMT function, we need to know the 24 hour time.
You can see on the bezel of this GMT Master 2 there are a total of 24 markers. These reference 24 hour time. You may have heard, in a war movie for example, someone referring to a time as oh six hundred hours or eighteen hundred hours. This is 24 hour time. Oh six hundred hours is 6:00am and eighteen hundred hours is 6:00pm. Think of a standard clock as being 24 hours instead of 12, with PM hours added on after 12:00pm. If 12:00pm is 1200 hours, then 1:00pm would be 1300 hours, 2:00pm PM would be 1400 hours, and so on. Then at midnight you have 2400 hours OR zero hundred hours (same thing).
We have time zones set up across the globe to line up with the rotation of the Earth. Our time here in the Central Time Zone of the U.S. is based on the standard of Greenwich Mean Time in Greenwich, England. This is why our watch is called a GMT, the acronym for Greenwich Mean Time. You may also see another standard of time measurement as being UTC, or Universal Time Coordinated or Coordinated Universal Time. UTC and GMT are functionally the same thing, but for our purposes here we’re going to use GMT.
Think of the time zone in Greenwich, England as basically being set at zero. Our Central U.S. Time Zone is five hours behind GMT. So, if our time here is 10:10am, that means it’s 3:10pm Greenwich Mean Time. This simple calculation is how we’re going to set our GMT watch. For a quick reference on time zones, simply do an online search for your time zone. We like using everytimezone.com since it clearly shows our current time zone as well as accurate time zones around the world now, in the past, or in the future. Really helpful in planning travel.
Now that we have a grasp on 24 hour time and time zones, let’s set up our GMT watch for travel. I’m going to be traveling to New York City for Wind Up soon, so I’ll use that time zone to set my watch.
All watches have the standard minute and hour hands for setting the current time, but a GMT watch has a 24 hour hand, or GMT hand. This is how we’re going to set our home time. Many GMT watches also have a rotating 24 hour bezel like our GMT Master 2. This is what we’ll use to set a third time on our watch.
The first step is, if you haven’t already, set your watch’s time to your current home time. It’s 10:10am where we are in the Central Time Zone of the U.S. Pull the crown out to the 2nd position and turn to set the current time and date. This is so we have a base reference for setting our two other times. And make sure your bezel is in its standard position, with the 24 hour triangle at noon. Triangle to triangle.
Next, we need to set our home time using the GMT hand. Home time is where you would be starting your journey. For us, that’s St. Louis. Pull the crown out to the third position and turn until the GMT hand matches your home 24 hour time on the bezel (or dial on some watches). If our current home time is 10:10am, we turn the GMT hand until it reaches just past 10 on the bezel. Ten hundred ten hours in 24 hour time. The minute hand will move too and will line up with ten minutes on the dial.
We’ve set our home 24 hour time with the GMT hand, so hop on the plane to New York City. After landing, I want to set my watch for the current East Coast time, which is one hour ahead of St. Louis. Simply pull your crown to position two and set the time one hour ahead using the hour and minute hands. In our case, that would be 11:10am. Now we know the current time where we are as well as the time back home in St. Louis.
Let’s say I make a really good business contact at Wind Up in New York, so now I have to quickly fly to London to continue making this deal. I need to know the time in London so I can book the right flight. This is our third time zone, which we’ll set using the rotating bezel.
I figure out that London is five hours ahead of New York, which makes it six hours ahead of St. Louis. The GMT hand on my watch is still set to my home time in St. Louis, so all I have to do to calculate London time is rotate my 24 hour bezel six clicks, or six hours. The trick with the bezel is that you rotate it in the opposite direction that you might think. To set a time ahead of you, you rotate counter-clockwise. To set a time behind you, you rotate clockwise. For London being six hours ahead of our home time, we rotate the bezel six clicks counter-clockwise. Now I can see, using our pre-set GMT hand, that the time in London is just past 1600 hours, or 4:10pm. And thanks to the GMT Master 2’s dual bezel colors with combinations like the Pepsi, the Rootbeer and the Batman, I can tell that the time I set it to is during daytime hours.
Having set my GMT bezel to the time in London, I can now book the right flight to arrive on time for my meeting.
So, there you have it. We just set three separate time zones on our GMT watch, the Rolex GMT Master 2. To quickly recap, we did the following:
- Learned the basics of 24 hour time and time zones.
- Readied our watch for setting.
- Set our home time using the GMT hand.
- Set our current time using the minute and hour hands.
- Set a third time using the rotating bezel.
You’re now ready to travel the world and always be on time in three separate time zones. The GMT Master 2 was the solution before smart phones, as long as you know how to use it. Read more about that here. And if you have liked any of the watch band/GMT Master combinations, don't forget to check out our watch band collections.
STL Time - 10:10am
NYC Time - 11:10am
London Time - 4:10pm
- Set your watch to your Current Home Time. Ours in American Central Time here in St. Louis.
- Set the GMT hand to your Current Home Time.
- Pull the crown out to the third position, which moves the GMT hand.
- Move the GMT hand until it matches your Home 24 Hour Time. Three PM would be 15:00, for example.
- For minute accuracy, simply continue turning the crown until the minute hand reaches the current minute. For 3:30pm, for example, set the GMT hand to 15:00 and the minute hand to 6 o’clock.
- Set the hour hand to the Current Time Zone. Let’s say we’re in Zurich, which is seven hours ahead of us.
- Push the crown in to the second position, which moves the hour hand.
- Move the hour hand until it matches your current time zone. For Zurich, this would be 10:30pm.
- Set the bezel to the Third Time Zone. We want to know the time in Tokyo, for example, which is another seven hours ahead of Zurich, and 14 hours ahead of St. Louis time.
- Align the bezel’s 24-hour position to 12 on the dial. Triangle to triangle.
- You want to rotate the bezel to correspond to your Home Time. Since Tokyo time is ahead of St. Louis time, we rotate the bezel counter-clockwise 14 clicks. Now we can see the time in Tokyo is 05:30 hours, or 5:30am.
- The lighter colored half of your GMT bezel, if you have a Rolex, corresponds to AM hours for quick reference.
- If we wanted to know a time that was behind our current time, we would rotate the bezel clockwise.
You can also check out the YouTube video on How to Use a GMT here!