At its most basic, a watch is there to conveniently remind you of the time with just the flick of your wrist. But for more timing capabilities, you can add what are known in horological terms as complications, which run the gamut of the stopwatch-like chronograph to a display of moon phases to a calendar window. Below are some of the most popular complications found in today’s watches.
One of the most ubiquitous complications, calendar watches include a small window showing the date, typically placed on the dial at 3 o’clock. You’ll also find some date watches that include the day of the week in a separate window. Most calendars count out to 31, requiring you to manually reset the date on those months that don’t have 31 days. Some date watches have smarter calendar complications. An annual calendar can run for a full year without resetting until you get to March (as February’s 28 or 29 days throws it off). But you won’t have to worry about resetting the date for a long time with a perpetual calendar watch, programmed to automatically adjust for the varying lengths of months as well as leap years to the year 2100.
Another popular complication in today’s watches is the chronograph, which enables you to use your watch as a stopwatch to time specific events as well as multiple laps. To start timing, you’ll press one of the pushers on the side of the watch case. Depending on the watch, you may press that pusher or a second one to stop the timing. Chronographs have two or three smaller subdials (also called totalizers or registers) placed on the dial face that display the seconds, minutes, and hours. Quartz chronographs can measure events down to 1/10 of a second, while their automatic counterparts can get as accurate as 1/5 of a second. In addition to timing your exercise, chronographs can be paired with a tachymeter scale (placed around the outside of the dial or on the rim of the bezel) to determine the average speed covered over a specified distance.
Note: Don’t confuse the term “chronometer” with a chronograph. Where a chronograph is part of a watch’s mechanics, a chronometer is a timepiece that’s been certified by the Controle Officiel Suisse des Chronometres (or COSC, the official Swiss chronometer inspection body) as being highly accurate. Only three percent of watches produced in Switzerland are chronometer-certified. To achieve this highly coveted certification, the movements are subjected to numerous tests over a period of 15 consecutive days and nights, in five positions and at three different temperatures. And a chronometer may or may not be a chronograph.
Moon Phase Indicator
More of an ornamental complication, lunar phase watches depict the illuminated portion of the moon as seen on Earth via an illustrated disc that rotates beneath the dial. Once set, the indicator will rotate completely once every 29 days, 12 hours, and 44 minutes.
Dual Time Zone and World Time
If you do a lot of traveling, a dual time zone watch (also called a GMT watch) can be handy as it will show you the current time where you are as well as the time in a second time zone. This is done either via an extra hand, twin subdials, or a 24-hour scale placed on the dial. If you need to keep track of business time on several continents, a world time watch typically displays 24 city names placed on the dial or bezel to represent each individual time zone. You can read the hour in a particular time zone by looking at the scale set next to the city that the hour hand is pointing to.
This is a generic term for a non-chronograph watch that displays information such as month, day, and date in two or three subdials.
Note: Chronographs, which are an added complication that provides stopwatch functionality, can be found on both quartz and automatic watch movements. Quartz chronographs can provide more accuracy, timing events down to 1/10 second compared to an automatic movement’s 1/5 second accuracy. Learn more about chronographs and other watch complications.