Understanding the GMT function and using the GMT hand and bezel to tell time
A GMT watch is one of the most useful tool watches for frequent travelers and those who do business across different time zones. Knowing how to use the GMT function allows you to tell time in two places simultaneously. How does this work? Let’s start by looking at the dial.
As you can see, in addition to the hour and minute hands, a GMT watch has a third hand – the GMT hand. On my Rolex Ref. 1675, the GMT hand is red. The GMT hand makes one complete trip around the dial every 24 hours. This hand, in conjunction with the bezel, is what you use to tell time in two different time zones at once.
With the bezel set straight up at 12 o’clock, the GMT hand is going to read the same time as the hour and minute hands. In this photo, you can see that it’s 4:11 p.m. and that the GMT hand is pointing to the 16 – so it’s 1611 hours, or 4:11 p.m.
To tell time in a different time zone, you will simply rotate the bezel.
For example, because my manager is in Los Angeles, I always like to be able to quickly tell LA time. Since Los Angeles is three hours behind the east coast, I rotate the bezel three hours back. Local time is 4:11 p.m. and you can see the GMT hand pointing to the 13 – so it’s 1311 hours in Los Angeles or 1:11 p.m.
To do a quick example in the opposite direction, say I want to know the time in Milan, which is six hours ahead. I’ll just rotate the bezel forward six hours. Again, it’s 4:11 p.m. local time and you can see that the GMT hand is point to the 22 so that means it’s 2211 hours or 10:11 p.m. in Milan. Simple.