A "complication" is any function beyond basic timekeeping. From simple date displays to astronomical calendars tracking centuries, complications represent watchmaking's highest art. Understanding them helps you appreciate—and choose—the right watch.
Simple Complications
Date Display: The most common complication. A window (usually at 3 o'clock) shows the current date. Requires manual adjustment for months with fewer than 31 days. Found on virtually every price level from Timex to Patek Philippe.
Day-Date: Adds the day of the week to the date display. Popular on Rolex Day-Date and Seiko 5. More useful than date alone for those who lose track of weekdays.
Power Reserve Indicator: Shows how much energy remains in the mainspring. Essential for manual-wind watches; helpful for automatics that aren't worn daily. Displayed as an arc or linear gauge.
Small Seconds: A sub-dial displaying seconds instead of a central seconds hand. Traditional and elegant, common on dress watches. Allows the center of the dial to remain uncluttered.
Calendar Complications
Annual Calendar: Automatically adjusts for months with 30 or 31 days. Only requires manual correction once per year—at the end of February. A practical middle ground between simple date and perpetual calendar.
Perpetual Calendar: Automatically accounts for varying month lengths and leap years. Requires no correction until 2100 (when the century exception to leap years occurs). A perpetual calendar "knows" the complete calendar for over a century ahead.
Moon Phase: Displays the current lunar phase through an aperture showing a moon disc rotating beneath. Astronomical moon phases cycle every 29.5 days. Most moon phases require correction every few years; high-end versions run for centuries without adjustment.
Chronograph
The chronograph is a stopwatch function using pushers to start, stop, and reset timing. Sub-dials display elapsed seconds, minutes, and sometimes hours. Originally developed for timing horse races and scientific experiments.
Standard Chronograph: Requires stopping the chronograph before resetting. The most common type.
Flyback Chronograph: Allows instant reset and restart with a single button press, without stopping first. Essential for pilots timing multiple legs of flight.
Split-Seconds (Rattrapante): Uses two chronograph hands that can be stopped independently, allowing timing of two simultaneous events. Among the most complicated chronograph types.
GMT / Dual Time Zone
GMT watches display a second time zone using a fourth hand completing one rotation every 24 hours, combined with a 24-hour bezel. Originally developed for pilots crossing time zones. "True GMT" movements allow independent adjustment of the local hour hand.
World Timer: Displays all 24 time zones simultaneously on a rotating city disc. More complex than GMT but allows reading any zone at a glance.
Alarm
Mechanical alarms vibrate or chime at a preset time. The Jaeger-LeCoultre Memovox and Vulcain Cricket are iconic alarm watches. Useful before smartphones made alarms ubiquitous—now more about mechanical appreciation than practicality.
High Complications
Tourbillon: A rotating cage containing the escapement, designed to counter gravity's effects on accuracy. Invented by Breguet in 1801 for pocket watches. In wristwatches, the tourbillon is primarily a demonstration of craftsmanship rather than practical necessity—the constantly changing orientation of a wristwatch already averages out positional errors.
Minute Repeater: Chimes the time on demand using tiny hammers striking gongs. Originally invented for reading time in darkness before luminous dials existed. Now represents the pinnacle of acoustic watchmaking—creating clear, beautiful tones from a mechanism smaller than a coin.
Equation of Time: Displays the difference between solar time (sundial time) and mean time (clock time), which varies up to ±16 minutes throughout the year. A complication for astronomical enthusiasts.
Astronomical Complications: Some watches display sunrise/sunset times, star charts, zodiac signs, or sidereal time. These "poetic complications" appeal to those fascinated by our relationship with the cosmos.
Grand Complications
Watches combining multiple high complications—typically perpetual calendar, chronograph, and minute repeater—are called "grand complications." These represent the ultimate expression of mechanical watchmaking. Patek Philippe, Vacheron Constantin, and A. Lange & Söhne produce the most celebrated examples.
Practical vs. Prestige
Most Practical: Date, chronograph, GMT. These complications solve real problems—tracking dates, timing events, managing time zones.
Balanced: Annual calendar, moon phase, alarm. Useful features that also demonstrate watchmaking skill.
Prestige/Art: Tourbillon, minute repeater, astronomical complications. These exist to showcase mechanical artistry rather than serve practical needs. They're expensive because they're difficult, not because they're useful.
Choosing Complications
Consider how you'll actually use the watch. A chronograph is valuable if you time things; useless if you don't. A GMT matters if you track multiple time zones; otherwise it's just visual interest. Don't pay for complications you won't use—unless you simply appreciate the mechanical artistry.
The best complication is one you'll actually use and appreciate. A simple three-hand watch worn with joy beats a grand complication sitting unworn in a safe.