A basic watch has one primary function: give you the current time. Anything above and beyond this is considered a complication.
The word complication has a negative connotation in most aspects of life. In watches, though, complication means anything that makes a watch more complex.
There are many different types of complications that have been developed over the years. Some are more useful than others.
I have come across most of the common complications you’ll see in this list, like chronographs and GMT. Still, I wanted to spend some time researching what else was out there.
To create this guide, I set out to make a comprehensive list that goes beyond the common complications you’ll see when shopping for a watch.
Because of this, some of the complications on this list are only found in very expensive or rare watches.
But, even if you won’t see them in affordable watches, they’re still fascinating and show the ingenuity and genius of watchmakers over the last few centuries.
So, let’s hop in with the most common complications you’ll see on modern watches, date complications.
1. Date Complications
Date complications provide the day of the month. They come in a few different varieties based on the way things are displayed.
The regular date compilation is one of the most common complications on modern watches.
The day of the month is shown in a small window, called an aperture, on the dial. It’s typically shown at 3 o’clock or 4 o’clock.
Sometimes the numbers alternate between red and black, which is known as a casino display.
A day-date complication adds the day of the week to the day of the month.
Usually, the weekday is abbreviated and shown next to the day of the month.
Sometimes, it’s not abbreviated and is located at 12 o’clock or 6 o’clock, and the date aperture is located elsewhere on the dial.
The big date complication displays the date in a larger and more legible way, hence the name.
In most cases, the date is shown in two apertures side by side, with the first displaying the numbers 0 through 3 and the second showing 0 through 9.
Big dates are usually located at 12 o’clock or 3 o’clock on the dial.
Instead of showing the date in an aperture, the pointer date complication has the days of the month arranged around the dial’s edge. A fourth hand points to the current date.
2. Full Calendar Complications
Calendar complications give you the day, date, and month. These complications can be very complex and expensive, depending on how often you have to adjust them.
A triple calendar takes the simple day-date complication and adds the month to it.
The wearer will have to adjust them often because they don’t account for months with less than 31 days.
So, five months out of the year, you’ll have to advance the display to show the correct information.
The annual calendar complication improves on the triple date.
This calendar accounts for the different lengths of the months. It only needs to be adjusted at the end of February.
A perpetual calendar is the most advanced in the category and an impressive feat for horology.
Building on the annual calendar complication, the perpetual calendar accounts for each month’s length and leap years. You won’t need to adjust the calendar until the year 2,100.
Chronographs are another of the more common complications on watches.
These usually feature two or three sub-dials, small dials on the larger main dial, and buttons on the side of the case, called pushers. Put simply, a chronograph complication is a stopwatch feature.
There are a few different types.
A simple chronograph typically has two pushers. One pusher, the top one, starts and stops the chronograph (stopwatch function) and the second pusher resets it.
A flyback chronograph allows you to quickly restart the chronograph from zero by pressing the bottom pusher. The watch’s second hand goes back to zero and starts timing.
A split-second chronograph has two second hands that start at zero together.
When a third pusher is pressed, one of the second hands stop while the other continues. This allows you to take a reading.
Pressing the third pusher again makes the paused second hand catch up to the other, and they continue on together again.
As a side note, some quartz chronographs have split-time functionality without two second hands.
Pressing the bottom pusher pauses the hands so a reading can be taken, but the watch still keeps time in the background.
Pressing the bottom pusher again advances the second hand to pick up where it should be.
This complication measures portions of a second on a sub-dial.
It is usually found on a chronograph, but sometimes outside of one and displays fractions of a second.
The hand makes one complete revolution around the dial every second.
5. Regatta or Yacht Countdown Timer
This is a very specialized complication built for boat racing. It was created to help countdown to the start of a boat race.
The regatta countdown timer provides a countdown between 15 and 5 minutes, depending on the watch.
A dual-time watch displays another time zone on the dial. Both timezones use the standard 12-hour display.
Generally, one timezone is shown in a sub-dial and the other on the main dial. Some watches have two dials of the same size.
A GMT complication also shows another time zone, but instead of two dials, it has an extra hour hand.
The GMT hand on these watches makes one revolution around the dial every 24 hours. The 24-hour index is found either around the outer edge of the dial or on a bezel.
You can set this to your home time, for example, and set the regular hour hand to the local time.
World-time complications allow you to see the time in cities around the world.
There are many different versions of these watches, and they display these times in different ways.
Most have a spinning disk with a 24-hour display, and the cities are stationary around the disk.
Hacking allows you to stop the second hand of the watch when pulling the crown, the knob on the case, out all the way.
With the second hand stopped, you can set the time precisely or synchronize your watch with someone else.
10. Small Seconds
The small seconds complication displays the seconds in a sub-dial, usually at 6 o’clock, rather than on the main dial with the hour and minute hands.
11. Equation of time
There is a slight difference between the time we usually use, called mean time, and the actual solar time.
Solar time is determined by the sun’s position at midday, which varies throughout the year, whereas mean time is an average. The difference can be +/- 20 seconds.
An equation of time complication shows these slight variations.
12. Moon Phase
This complication displays the moon phase through the lunar cycle, either through an aperture on the dial or with a dedicated hand.
The aperture display shows the moon moving across the aperture from new to full and back again.
This is an exclusive (and expensive) novel complication that is a mechanical model of the solar system on a watch.
The planets’ orbits are displayed as they move around the sun.
14. Day-Night Indicator
As you can tell from the name, this complication tells you whether it’s day or night.
These are usually included with dual-time complications.
Because the dual-time follows the 12-hour format instead of the 24-hour format, this helps you keep track of AM and PM in the other timezone.
15. Power Reserve indicator
This complication is a gauge that displays how much power a mechanical watch has in its reserve. When the gauge indicates power is low, you’ll know it’s time to wind the watch.
They can be found on manual or automatics.
16. Jumping Hour
A jumping hour complication moves quickly from one hour to the next.
It can be a digital display in an aperture, meaning it shows the hour in a number format, or have a traditional display with an hour hand.
Every 60 minutes, the hour displayed jumps to the next one.
17. Dead-Beat Seconds
This complication has the second hand of a mechanical watch move once every second.
This complication essentially makes a mechanical movement, which has a sweeping second hand, act like a quartz movement, which ticks once every second.
A barometer complication adds an internal barometer to a watch. This display is useful for forecasting the weather.
It is extremely rare on mechanical watches.
A thermometer complication displays the temperature on the watch dial.
This is another rare complication on a mechanical watch, but common on digital quartz watches made for outdoor activities.
An altimeter allows you to determine the altitude you’re at. This works with an internal barometer.
Altimeter complications are helpful for mountaineering or aviation.
21. Depth Gauge
Some dive watches have a built-in depth gauge.
This complication allows you to see the depth of a dive on the dial of the watch. Some also display the accent rate.
You’re probably accustomed to finding an alarm on digital watches, but these complications can be found on analog ones too.
On an analog watch, you can set the alarm to a time within 12 hours by setting an additional central hand.
A sonnerie complication has an internal chime that sounds the time periodically.
There are two types: a petite sonnerie and a grande sonnerie.
A petite sonnerie strikes the time every hour, and a grande sonnerie strikes the time every quarter-hour.
24. Minute Repeater
A minute repeater is another type of complication that sounds the time with an internal striking mechanism.
The difference between a sonnerie and a minute repeater is that, for a minute repeater, you have to press a lever on the watch case for it to sound the time.
A tourbillon is a complication that was created in an era when most people used pocket watches.
A pocket watch would remain in the same position for most of the day. This creates position-related timing errors in mechanical watches.
A tourbillon fixes this by housing the balance wheel, hairspring, and escapement in a small rotating cage. The cage rotates periodically and eliminates positional errors.
Today, they are not as vital because a wristwatch is in many positions throughout the day. They are beautiful and complex complications, though, that are highly desired.
What to do Next?
As you’ve seen there are a lot of different watch complications out there. Don’t let this overwhelm you, though.
To help you find the watch with everything you need, check out my ultimate affordable watch buying guide.