Seeing the word chronometer on a watch’s caseback sends a thrill through the minds of watch enthusiasts—they know they’re looking at an incredibly accurate timepiece. But for those just getting started on their horology journey, this word won’t mean much. In fact, many novices mix up the term chronometer with chronograph.
While it’s an easy mistake to make with the words being so similar, it’s important to know the difference between the two terms when selecting your favorite watch. Once you understand each term, you’ll be one step closer to calling yourself a seasoned watch wearer.
What Is a Chronometer?
To understand and remember the difference between a chronometer and a chronograph, it helps to know the origin of each word. Chronometer begins with the prefix chrono, meaning “time” in Greek.
The second half of the word is meter. When asked to picture a meter, most people think of a dial with a rotating hand that measures something. That’s exactly what a chronometer does—at its core, it measures time.
With this knowledge, you’re probably wondering: isn’t every watch a chronometer? Well, not exactly. While every watch measures time, not every watch does it accurately enough to be deemed a chronometer.
To receive the title of chronometer, a watch’s movement must be tested by the unbiased Contrôle Officiel Suisse des Chronomètres (COSC). The COSC conducts the same test for every brand and model of watch movement.
The chronometer test lasts a whopping 15 days. During that period, movements are tested in five different positions and at three temperatures ranging from 46º F to 100º F. The COSC also gathers other measures such as average daily rate, greatest variation in rate at different positions and temperatures, and rate resumption.
Over the 15 days, each movement must maintain an accurate gauge of time within 6 seconds fast or 4 seconds slow per day. If the movement can pass this strenuous test, the COSC will grant it the title of an official chronometer.
How Do I Know My Watch Is a Chronometer?
Many luxury watch brands pride themselves on only creating COSC-certified chronometers. Therefore, whether you have, for example, a Breitling Navitimer, Aviator, Chronomat, or other model, you also have a chronometer.
If you’re not sure, there’s a simple test you can conduct. Remove the watch from your wrist and take a look at the engravings on the caseback. If you see “chronometer” on the caseback, you’ll know you have a genuine chronometer that will tell time exceptionally accurately.
What Is a Chronograph?
Like the word chronometer, chronograph begins with the Greek prefix chrono. A chronograph, however, records time rather than tells time. To easily remember the difference, just picture a graph like you’d see in a math or science class—it’s a way to record measurements and data points.
Essentially, a chronograph is a technical term for a stopwatch. Therefore, while a watch can be a chronometer, it can feature a chronograph.
Whether or not your watch has a chronograph, it doesn’t affect the timekeeping abilities of the watch (as long as your movement is running smoothly and you’re not overdue for your watch’s repair, of course). A chronograph is simply an additional feature of a watch, also called a complication.
How Do I Know if My Watch Has a Chronograph?
Not all watches have a chronograph feature. If you’re new to watches, take a look at your owner’s manual to see whether it features a chronograph. Otherwise, a quick glance at the watch’s face will show you if there’s a subdial for chronometer measurements.
How Do I Keep My Watch’s Chronometer and Chronograph Running Smoothly?
If you’re just beginning your love affair with watches, it can be challenging to keep track of the difference between a chronometer and a chronograph (and all the other obscure watch terms). Don’t worry, though—with the visualization tool of a meter vs. a graph, you’ll get the hang of it.
The next thing to consider is keeping your watch in perfect working order. The wonderful thing about a certified chronometer is that your watch can undergo all sorts of pressure and temperature changes without losing its timekeeping abilities. However, no watch can maintain perfect consistency for a lifetime—even in luxury watches’ brilliantly engineered movements.
All kinds of things can go wrong with your watch’s movement over time, causing it to lose or even gain time. That’s why it’s vital to keep up with your watch’s servicing schedule and bring it in for a repair the minute you notice anything that seems off.
To keep your watch’s chronometer movement, chronograph, and other complications running at peak performance, remember to schedule regular servicing with a trusted watch repair service. This will not only keep your keepsake looking beautiful but also ensure that it lives up to the accuracy certified by the COSC for years to come.
