Hamilton Khaki

Article By: Logan Hannen

What is up, watchfam?! Today, we’re going to take a look at the buzziest of buzzwords in the Swiss watch world: chronometer.

Now, as you might expect, it’ll be helpful for us to define the word before we get into what it actually means. Is that a bit of a strange statement? Maybe, but you’ll see what we mean in a second.

In short, a chronometer, according to Stephen Pulvirent of HODINKEE and Bloomberg, is just a fancy word for a really super accurate watch. That sums up the concept pretty well, I think. The title of “chronometer” is bestowed upon pieces which consistently perform within a certain degree of accuracy, as determined by a governing body, the International Organization of Standardization. The Contrôle Officiel Suisse des Chronomètres, or COSC, is responsible for testing that accuracy, according to the COSC website.

The COSC is an organization that more or less functions as a sort of testing institute, much the way the ISO is for diver watches (among other things). Unlike the ISO, which does also handle a wide range of testing purposes, the COSC is solely responsible for the testing and management of timepieces and their accuracy. Sounds like a pretty cool job to me.

So what kinds of standards does the COSC require of watches in order to earn the name “Chronometer”? After an extensive, 15 day testing period, the piece must perform within -4/+6 seconds per day. We’ve covered time losses and gains before, so be sure to check out that article to learn more! Regardless, it’s important to remember that accuracy isn’t everything, generally (though, if that’s something you’re passionate about, then by all means get obsessed! It’s your hobby, too!). What it does do, though, is act as a sort of testament to the overall quality of the piece, since it isn’t easy being certified a Chronometer!

The official seven criteria are:

  • average daily rate
  • mean variation in rates
  • greatest variation in rates
  • the difference between rates in horizontal and vertical positions
  • largest variation in rates
  • variation in rate depending on temperature
  • rate resumption

That about does it for this edition of “Watch 101.” Now that you know what makes a watch a Chronometer, hopefully you’ve got a better sense of why this almighty horological buzzword does actually deserve some of its buzz. It’s some serious commitment to quality, usually done by a well respected manufacturer, and one who definitely knows how to keep it classy, watchfam.