Complications
The extra functions a watch performs beyond telling the time: chronograph, GMT, date and more.
A complication is any function a watch offers beyond hours, minutes and seconds. It ranges from the chronograph and GMT to the date and the power-reserve indicator.
The terms in this section explain in plain language what each complication does and whether you actually need it day to day.
- Caller vs True GMT
- Caller and true GMT are the two ways a GMT watch can work. On a true or flyer GMT, the local hour hand jumps independently as you travel, which is ideal for trips. On a caller or office GMT, only the 24-hour hand moves, which suits tracking a second zone from your desk.
- Chronograph
- A chronograph is a stopwatch complication that times an elapsed interval without disturbing normal timekeeping. Side pushers start, stop and reset the counter, with the seconds usually supported by minute and hour sub-dials. It comes in both quartz and mechanical versions.
- Date Window
- A date window is a simple complication that shows the day of the month through a small aperture on the dial. It is the most common complication of all. Variants include day-date, big date and a pointer date. Most need manual correction after short months, and many offer a quickset through the crown.
- GMT
- A GMT is a complication that displays a second time zone with an extra 24-hour hand, normally read against a 24-hour bezel or track. It lets you follow home and local time at once, which is why travellers favour it. The affordable Seiko 5 GMT is one such example.
- Moonphase
- A moonphase is a complication that displays the current phase of the moon, from a thin crescent to a full disc, through a small aperture on the dial. It is largely decorative and traditional rather than practical, driven by a 59-tooth wheel. Even a precise version drifts only a day every few years.
- Tachymeter
- A tachymeter is a fixed scale around the bezel or dial rim that converts elapsed seconds into speed. You start the chronograph at a marker, stop it after a known distance, and the seconds hand points to the average speed. It needs a chronograph to be used.