Monochrome Watches
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The Citizen Calibre 0100, the Most Precise Quartz Wristwatch Ever, Fully Explained

The +/- 1 Second Per Year Precision isn't a small achievement, as explained by the brand's Managing Director.

| By Brice Goulard | 2 min read |

Precision has always been key for watchmakers. Far beyond the development of complications, having a watch that displays the time in the most accurate possible way was and still is (or should be) the raison d’être of watchmaking. Mechanical watches can go up to +/- 1 second a day; it’s not easy to achieve, but possible. To surpass these standards watchmakers have to come up with different solutions. One of them is the Citizen Calibre 0100 – and yes, this is the most precise quartz wristwatch ever made, with a declared precision of +/- 1 second… per year!

Quartz watches are not our thing here at MONOCHROME. We love the beauty of gears and wheels, all driven by the simple mechanical force of an unwinding spring. However, let’s be realistic, mechanical watches are a thing of the past, or at least of passion. There’s no rational reason to own a mechanical watch other than our own pleasure and the beauty of handmade luxury objects. And although we stick to our guns when it comes to quartz, there is no denying that what Citizen has achieved – albeit quartz-driven – is an incredible achievement.

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In the video at the top of this article, we talk to Norio Takeuchi, Managing Director of Citizen, in order to understand how it has been possible to create a watch that can display the time with less than a 1-second deviation per year. Yes, you read right, 1-second precision per 365 days, meaning that this watch is 99,9999969% accurate… This is, to our knowledge, the most accurate quartz wristwatch ever created to date, by far.

As explained in our in-depth article, the Citizen Calibre 0100 is a solar-driven watch with a new-generation quartz movement. What’s new here is the regulator itself, to be precise an AT-cut type crystal oscillator rather than a traditional tuning fork crystal oscillator. AT-cut crystal oscillators vibrate at the impressive frequency of 8,388,608 Hz compared to the traditional 32,768 Hz resonators used for standard quartz movements – thus, 256 times faster than a classic quartz movement and a few millions time faster than a mechanical watch.

The impressive precision obtained is set at +/- 1 second per year, which is 100 times more precise than a standard quartz movement (which is about +/- 15 seconds per month) and, of course, far more precise than any mechanical chronometer watch (-4/+6 seconds a day) or the already very precise Spring Drive by Seiko (about +/- 10 seconds per month).

Because images and spoken words are better than these lines of text, take a look at our video at the top of this article to understand all about the impressive Citizen Calibre 0100 and its astonishing precision. More details at

8 responses

  1. Wouldn’t one of the weird atomic wristwatches, like the Bathys Cesium 133, be the most accurate wriswatch ever made? Although that barely qualified as a wristwatch…

  2. Just a slight correction to the article: it isn’t necithe case that AT cut crystal oscillators have an 8.4 MHz frequency. Indeed, there are a fair few examples of quartz watches with AT cut oscillators in 2.4 MHz and 4.2 MHz guises. Likewise, there is nothing to say that a tuning fork shaped oscillator has to have a frequency of 32 kHz. There have been notable examples oscillating at 8 Hz and 16 Hz (among others).

  3. I have a rule of never writing comments under watch articles, and always stick to that principle.

  4. Like Zanpa says, I think the true Cesium133 atomic clock wristwatches like the Bathys or the Hoptroffs win ‘most accurate wristwatch’ at about 1 ms/year (10 ms/year for the Hoptroffs in ‘low power’ mode).

    The Hoptroff no.1 (or 2 and 3) is actually somewhat wearable at 52 x 42 x 19.5 mm (the Bathys is worse)

  5. @ Marco @ Zanpa – Just to avoid confusion, we slightly changed the article to “Most Precise Quartz Wristwatch”, even though we’ll hardly consider the Bathys Cesium 133 as a wristwatch, or anything serially produced.

  6. I love this piece. Love it. Practically every watchmaker can learn from it. It is a technical tour-de-force but classically proportioned and elegant.

  7. The only thing they need now is this accuracy with Atomic timekeeping, Bluetooth & GPS.

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