Guides

How to set and use a GMT watch

Set local time, home time and the 24-hour hand, tell a flyer GMT from a caller GMT, and track a third time zone with the bezel.

Published

What the fourth hand does

A GMT watch has a fourth hand that goes round once every 24 hours and points to a 24-hour scale on the bezel or the dial. It shows a second time zone, and because it runs on 24 hours it also tells you whether it is day or night there.

Which kind do you have?

  • Flyer, or traveller, GMT: the middle crown position jumps the local hour hand in one-hour steps while the watch keeps running, and the date follows it. The 24-hour hand stays on home time. The Rolex GMT-Master II, the Tudor Black Bay GMT and the Grand Seiko GMTs work this way.
  • Caller, or office, GMT: the middle crown position jumps the 24-hour hand instead, and you set local time the normal way. Watches with the ETA 2893, Seiko NH34 or Seiko 4R34 movements work this way.
  • Not sure? Pull the crown to the middle position and turn it gently. Whichever hand jumps tells you.

Setting a flyer GMT

  1. Pull the crown all the way out. Set the 24-hour hand and the minute hand to home time, checking day or night on the 24-hour scale. The hour hand moves with them.
  2. Push the crown in on the minute using the sync countdown to get the seconds right.
  3. Pull the crown to the middle position and jump the hour hand to local time. Going past midnight moves the date, backwards too.

Setting a caller GMT

  1. Pull the crown all the way out and set local time with the hour and minute hands. Turn forward through midnight to put the date on the right half of the day, and avoid the hours around midnight, as the date-change guide explains.
  2. Push the crown in on the minute.
  3. Pull it to the middle position and jump the 24-hour hand to the second time zone.

A third time zone

If the 24-hour bezel turns both ways, turn it by the hour difference to a third zone and read the 24-hour hand against the turned bezel. Turn it back to 24 at the top to read the second zone again.

Travelling

A flyer is made for this: on landing, jump the hour hand to local time and leave home time on the 24-hour hand. The same jump is the quickest way to deal with daylight saving time.