WATCH BASICS
Watch complications explained
“Complication” is just watch-speak for any function beyond telling the time. Here’s what the common ones actually do — from the humble date to the mesmerising tourbillon — and which are worth seeking out.
The complications you’ll actually meet
Roughly from most to least common.
Date & day-date
The most common complication of all — a date window, sometimes paired with the day of the week. Simple, and genuinely useful.
GMT / dual time
A 24-hour hand tracks a second time zone. The traveller’s favourite: local time on the main hands, home time on the GMT hand.
Chronograph
A built-in stopwatch operated by pushers, with subdials to record elapsed seconds, minutes and hours.
Moonphase
Displays the current phase of the moon on the dial — pure romance, and a favourite of dress-watch lovers.
Power reserve
An indicator showing how much stored energy is left before a mechanical watch needs winding.
Tachymeter
A scale (usually on the bezel) that, with the chronograph, measures speed over a known distance.
Annual & perpetual calendar
Calendars that track months of different lengths — the perpetual even handles leap years, in theory forever.
Alarm, world time & tourbillon
From a wrist alarm to a full world-time display, up to the gravity-defying tourbillon — the high art of watchmaking.
Movements
Automatic vs quartz, with live dials.
Watch glossary
Every term, explained.
Watch brands
Explore who makes what.
Frequently asked questions
What is a watch complication?
A complication is any function a watch performs beyond telling the basic time — the date, a chronograph (stopwatch), a second time zone (GMT), a moonphase, a calendar, and so on. The more complications, generally the more complex and expensive the movement.
What is the difference between a chronograph and a chronometer?
A chronograph is a watch with a built-in stopwatch, operated by pushers with subdials to time events. A chronometer is a watch whose movement has passed an independent accuracy test such as COSC. They sound alike but mean completely different things — a watch can be either, both, or neither.
What does a GMT watch do?
A GMT complication shows a second time zone using an extra 24-hour hand (and usually a 24-hour bezel or scale). It’s the classic traveller’s complication — you keep local time on the main hands and home time on the GMT hand.
Which watch complications are actually useful?
The date and a GMT are the most genuinely practical for everyday life, and a chronograph is handy and fun. Calendars, moonphases and tourbillons are more about craftsmanship and beauty than daily utility — which is a perfectly good reason to love them.
What is the difference between an annual and a perpetual calendar?
An annual calendar automatically accounts for months of different lengths but needs a manual correction once a year (at the end of February). A perpetual calendar goes further, correctly handling February and leap years, so in theory it never needs adjusting for the date — a pinnacle of watchmaking.
Learn the language of watches
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