Watch Complications Explained

What is a complication?

A complication is any function a watch performs beyond showing hours, minutes and seconds. Here are the most common, roughly from simplest to most complex.

Everyday complications

• Date: shows the day of the month, usually in a small window
• Day-date: adds the day of the week
• GMT / dual time: tracks a second time zone
• Power reserve indicator: shows how much energy is left in the mainspring
• Chronograph: a built-in stopwatch

Calendar and astronomical complications

• Moonphase: shows the phase of the moon through a window on the dial
• Annual calendar: knows the length of each month, needing correction only once a year at the end of February
• Perpetual calendar: accounts for month lengths and leap years, and can stay correct for decades

Grand complications

Watches that combine several of these are among the most complicated mechanical objects ever made by hand.

• Tourbillon: a rotating cage for the escapement, invented by Abraham-Louis Breguet and patented in 1801 to average out the effects of gravity
• Minute repeater: chimes the time on tiny gongs at the push of a slide
• Split-seconds (rattrapante) chronograph: times two events that start together but finish separately