In watch terminology, a complication is any function other than telling the time. The more complications a watch has, the more difficult it is to build the mechanical movement that drives the watch. If a watch combines many complications — particularly intricate ones — it’s called a “grand complication.”
Very few watch brands have the capability of producing grand complication timepieces given the amount of skill, knowledge, and time it takes to develop the movements. You’ll often hear the terms "high horology" or "haute horlogerie" to describe these types of complicated watches.
While high horology timepieces are few and far between, watches fitted with a few complications are not. Here's an overview of the most popular watch complications offered by luxury watch brands.
While some complications are purely decorative, others can be quite useful, particularly for travelers. Common complications include features like world timers, dual time zones, and alarms. While not strictly necessary, these complications can be very handy for anyone who frequently jets off to different time zones. Of course, luxury watch brands often take complications to the next level with features like moon phase indicators and tourbillons. For the avid traveler, a watch with one or more complications can be a real asset.
A chronograph watch includes a stopwatch function. A traditional chronograph watch has two pushers on the case, a central chronograph hand (in place of a normal seconds hand), and two or three subsidiary dials. The two pushers, which are normally positioned above and below the winding crown, serve to start and stop (upper pusher) and reset (lower pusher) the chronograph hand.
The subsidiary dials include counters to track how many minutes and hours have elapsed since the chronograph hand was activated. Although not a requirement, many chronograph watches will include a tachymeter scale, which measures units (miles and/or kilometers) per hour. Chronograph watches with two subsidiary dials are often called bi-compax while those with three subsidiary dials are called tri-compax.
A flyback chronograph (a.k.a. retour-en-vol) does not require the chronograph hand to be stopped before resetting it. A split-seconds chronograph (a.k.a. rattrapante) features three pushers and a pair of chronograph hands to time two events that begin together but end separately (like in a race.) Finally, there’s also the single-pusher chronograph (a.k.a. monopoussoir) where one pusher starts, stops, and resets the chronograph hand.
While people often confuse the terms, chronographs and chronometers are not the same things. A chronometer is a watch that has been officially certified to meet specific accuracy/precision ratings, while a chronograph is a watch with a stopwatch function. In Switzerland, the Swiss Official Chronometer Testing Institute (COSC) is in charge of testing and certifying chronometers.
Although the above complications are the most popular ones used in luxury watches, there are plenty of other watch complications available too.
A power reserve indicator tells the wearer how much energy the movement has before it requires winding. A typical modern luxury watch can have anywhere between two to ten days of power reserve.
A day/night indicator differentiates between A.M. and P.M. hours of the second time zone display.
A moon phase display shows the lunar progression, from new to full, over its complete cycle (29 days, 12 hours, 44 minutes, and 2.8 seconds.) It's typically displayed in a semi-circular window on the dial, to obscure the correct portions of the moon depending on the current phase.
An alarm watch will either make a sound or vibrate at a pre-determined time.
Striking complications sound out the time via tiny hammers striking tiny gongs either on demand or automatically. These are some of the most difficult complications to make and were invented before electricity so that the owner could know the time in the dark. The most famous are minute repeaters, which chime the hours, quarters, and minutes on demand.