Watch Types
GMT vs World Timer: Watches for Travelers
How GMT, dual-time and world-time watches work, the difference between a "flyer" and a "caller" GMT, and which suits how you travel.
By Brandon Volosov · 4 min read · Updated October 9, 2026
GMT watches
A GMT watch adds a fourth hand that goes around the dial once every 24 hours, read against a 24-hour bezel or scale. Set it to home time and you can read two time zones at a glance; turn the bezel and you can track a third. The Rolex GMT-Master was developed in the 1950s for airline pilots.
"Flyer" vs "caller" GMTs
On a "flyer" or "true" GMT, the local hour hand jumps independently, so when you land you can change local time (and the date) without stopping the watch. On a "caller" or "office" GMT, the 24-hour hand is set independently instead, which suits people who stay home but keep track of colleagues abroad. Flyer GMTs are usually more expensive.
World timers
A world timer shows the time in all 24 major time zones at once, using a ring of city names and a rotating 24-hour ring. They're beautiful, especially with map dials, and ideal for people who work across many countries.
Which is right for you?
- Frequent flyer: a flyer GMT
- Working with one other time zone from home: a caller GMT or dual-time watch
- Calling the whole world: a world timer