Watch complications explained
Every common watch complication in one place, from the date to the perpetual calendar: what each one does and how to set and use it.
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What a complication is
Anything a watch does beyond telling the hours, minutes and seconds. Each one adds parts to the movement, and some add a little care in how you set the watch.
Calendars
- Date: the most common complication, and the one most often damaged by setting it at the wrong time. When not to change the date.
- Day-date: adds the day of the week. How to set it.
- Annual calendar: knows 30- and 31-day months, so it needs one correction a year, on 1 March.
- Perpetual calendar: knows February and leap years, correct until 2100. How to set one.
- Moonphase: shows the moon's phase, and drifts by about a day every two years and eight months. How to set it.
Timing
- Chronograph: a stopwatch, usually with a tachymeter for speed. How to use it.
- Dive bezel: not strictly a complication, but a turning timer on the case. How to use it.
- Flyback: a chronograph that resets and restarts with one press.
Time zones
- GMT: a 24-hour hand for a second time zone. How to set and use one.
- World time: a ring of city names that shows the hour in every time zone at once.
Others
- Power reserve indicator: shows how much the mainspring has left before the watch stops.
- Alarm: a mechanical alarm with its own mainspring that buzzes at a set time.
- Minute repeater: chimes the time on tiny gongs at the press of a slide. Among the most complex and costly complications.
- Tourbillon: the balance in a rotating cage, invented to even out errors from position. Today it is mostly a showpiece.