Watch Accuracy: Rolex vs. Casio


Rolex Yachtmaster perfectly preserved

“A Rolex will never be as accurate as a cheap quartz watch.” That’s a commonly held belief by people who sniff at expensive automatic watches. Is it true? What about the reverse? Does more money buy you greater accuracy? Put on your best water resistant watch and join me for a data dive into the strange world of watch accuracy. . .

Casio Watch Accuracy

Depending on the model, Casio claims their battery powered watches achieve +/- 15 to 20 seconds accuracy per month. Using the best case of 15 seconds per month, Casios average 0.5 seconds per day (s/d).

The data above was gleaned from my personal collection. As you can see, my Casios exceed the manufacturer’s accuracy claim. My worst performing Casio: a vintage G-Shock G-7800 Super Square (below). It clocks-in at 0.48 s/d, right at the edge of Casio’s best case 15 seconds per month accuracy claim.

[Note: none of these samples are equipped with Casio models with Multi-Band 6 technology, which syncs watches with Uncle Sam’s atomic clock on a nightly basis.]

Rolex Watch Accuracy

Rolex Yachtmaster serviced

Rolex uses their own accuracy testing protocol: the Superlative Chronometer Standard. A Rolex so labeled is guaranteed accurate to -2/+2 seconds per day. Over the course of 15 weeks, my Rollie beat the standard by a mile.

The Yachtmaster was accurate to -0.35 s/d, or about -10.5 seconds per month. Considering the fact that the Rolex is a purely mechanical watch (driven by a spring), losing a third of a second per day is truly remarkable.

Rolex vs. Casio Watch Accuracy

watch accuracy Rolex vs. Casio

Paired against my five worst performing Casios, the Rolex is the more accurate watch. Geneva’s favorite son refutes the notion that “any quartz will keep better time than a Rolex.” The Rolex is also more accurate than my second worst Casio, a recent G-SHOCK model. OK, sure. All my OTHER Casios beat the Rolex. But not by much.

That done, let’s take a look at this from the price/accuracy perspective, asking the tough questions . . .

Mo’ Money = Mo’ Accuracy for Autos?

The following sample includes three automatic watches (’cause that’s how many I own). While it’s true that my most expensive watch is the most accurate, the differences between them are far from proportional.

watch accuracy mechanicals compared

The Lum-Tec 300-M3 ($795) is my least expensive auto. It’s powered by a pedestrian Miyota 9015 automatic movement. The Lum-Tec delivers an astonishing sub-second per day accuracy. It easily outperforms my COSC “Swiss Chronometer” Breitling.

Mo’ Money = Mo’ Accuracy for Quartz?

In my admittedly small and seemingly random sample, watch accuracy seems inversely correlated to price. The cheapest Casios in my collection are the most accurate. The leader of the pack: the venerable and vaunted Casio MDV-106 Duro.

Out of my three Duros, the best of the bunch clocks in at +0.11 s/d. That’s +3.3 seconds per month or +39.6 seconds per year. Less than a minute off PER YEAR. The Duro costs about $50 on Amazon (no commission on link).

My second most accurate Casio is also the cheapest. The $25 Casio “Royale” AE-1200WH averaged -0.12 s/d or 3.6 seconds per month accuracy, or 43.8 seconds per year.

My G-Shock GST-S300G is my most expensive non-atomic Casio. The $260 watch is accurate to +0.38 s/d, which is less accurate than my Rolex (see first chart).

watch accuracy G-SHOCK


This brief and not-particularly-scientific survey of watch accuracy didn’t include HAQ or thermo-compensated quartz watches, or a wide range of high end mechanical pieces (don’t get RF started on tourbillons). Even so, I think it’s safe to say there’s no direct correlation between watch price and watch accuracy.

Whether comparing mechanical to quartz, mechanical to mechanical, or quartz to quartz, your mileage may vary, regardless of the price paid. If accuracy is your thing, you can find your bliss at all price points.


  1. I love watches with automatic and mechanical movements, and I think people get too hung up on the accuracy question. Durability is the tiebreaker. In hindsight, any mechanical or automatic watch that I wore on a daily basis when teaching or looking after kids didn’t last long.

    • My Rolex YM lasted a long time, and by all appearances took a beating, for around 15 years of daily wear… before it quit on me. Got it serviced late last year, and I expect to get another 15+ years out of it before needing an overhaul. It may last even longer, given that I don’t wear it daily anymore (and it’s now part of a large rotation).

      • Yeah, that is one thing I love about automatic and mechanical watches: no batteries. I have a Vostok Amphibia (automatic movement) that has seen a lot of wear and taken a beating over the years. I’ve actually done some really stupid things with it, but these days, I’d rather err on the side of caution and wear my “newer” automatic or mechanical purchases around the office or at home instead of at the beach with the kids. I still wear the Vostok Amphibia as a beater on family trips to the beach or the pool.

        • Those Russian watches definitely have a following. I have not ventured down THAT rabbit hole… yet.

          The 24-hour watch guys like Russian watches, and the Ruskies seem to have an affinity for 24 hour watches. I’ve got a 24-hour watch pre-ordered from the non-Russian Lum-Tec. Looking forward to it.

          • I like the Vostok Amphibia, but in hindsight, the money would have been better spent on an SKX007. Not a knock on Vostok, just that Japanese watches are more my thing, and I’ve been priced out of the latest dive watch offerings from Seiko.

    • I dig accuracy, but I keep it all in perspective. As long as they’re within the manufacturer’s parameters, I’m good. Even a little off those parameters is OK. But, I admit being fascinated by how accurate they CAN be. That my Rolex is currently running 1/3 second per day is amazing, considering it’s a mechanical watch.

      And, my Lum-Tec with a Miyota running less than a second off per day?? Yippeeee!! LOL!

  2. Very interesting study on your available timepieces, Anecdotally I have also observed that “If accuracy is your thing, you can find your bliss at all price points.” This observation I base on comparing accuracy of watches on winders for extended time periods (months) against atomic time. I have been surprised to have wrist art worn for beauty/show/jewelry exhibit accuracy better than pieces being touted for their COSC (or other) certification. I have gained respect for the former brands and lost it for the latter. Given poor correlation between price and “accuracy”, this is one reason I have little interest for chronograph complications. It would be off putting (to me) to be wearing a shitty stopwatch whose features take up most of the watch’s face. Poor time keeping I can accept, if expected, as I always have accurate time keeping close at hand.

  3. I am generally one that loves to gloat over the superiority of quartz. Getting experience with a few mechanical watches made me more tolerant, as none are that bad, and it’s just a whole different game unless you actually keep them consistently wound for multiple months, which I don’t.

    I expect quartz to be set exclusively at daylight saving time changeovers, and a deviation of more than a minute and a half or so over that approximate half year is deemed unsatisfactory. For mechanical, I expect that it’ll wind down within a week or so, and the ability to stay within a minute or two for a week is good enough.

    I could rant about how the exactness of digital is maddening and the sloppiness of unhacking watches with lackluster power reserves is liberating. When I hear digital hourly chimes straying by a few seconds, it bugs me. When a stopped mechanical can only be set to within half a minute to begin with, barring absurd efforts, it’s hard to care.

    I kind of share this OCD while also knowing that it really just doesn’t matter. No flight is leaving without me, no assassination will be botched. If I’m a minute late tuning in to some show, I’m fine with that.

    • It’s more of a fascination than an obsession with me. I enjoy tracking accuracy just to see how good it CAN be. It’s not that I NEED it to be. I keep my autos on winders, so I can “grab-and-go” without having to set and wind them. I won’t reset them unless the time is WAY off. That will take a while.

  4. First of all, thank you for your work! I was looking for some real life data of Rolex accuracy, and I found only your page!

    I miss only one thing: you did not mention if you were wearing all of the watches during your test? I guess it does not really matter for the quartz watches, but what about the mechanical watches?

    Reading your article I do not understand the Swiss guyz… They basically boycotted the Neuchâtel Observatory Chronometer trials after 1967, when Seiko started to win. Here is the database: The best ever Seiko had the “N-number” of 2.04, which is less than 0.1 sec/day. So if Rolex is able to make watches in big batches that are accurate to around 0.3 sec/day, then I am pretty sure a competition like that would be interesting! Just for fun, not for judging…

    BTW, don’t you have a few mechanical GS watches to do some tests too? 😉

    And finally, I have a “Seiko Solar Titanium”, purchased 10 years ago for $200, and it is +/-1 sec per month.

  5. There was this Casio watch I used to have while I was at school about 40 years ago. It had a nifty feature whereby you could switch out the stopwatch for a number of other functions such as World Time by holding the Mode button for a few seconds. However I discovered an undocumented function whereby if you held down both Select and Set for a few seconds then it would enter a calibration screen where you could use the Select and Set buttons to adjust its accuracy from -15 to 15 which appeared to represent increments of 1 second per month, which was fortunate since it otherwise gained half a second daily. Sadly I lost it during my first year of university.

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