Automatic Watch Accuracy Explained for the Modern Timekeeper

In this article, I’ll break down everything you need to know when it comes to automatic watch accuracy!

Have you heard that Andy Warhol famously wore an unwound Cartier?

I love talking about how we don’t often use watches to tell time anymore. It’s funny coming out of someone like me, a general minimalist who owns three suits but too many watches.

I bring it up because it’s a good segway into the plethora of reasons we still wear them. 

Yet, good automatic watches are still highly in demand. Part of this has to do with the fact that accuracy and precision are a testament to good engineering (one of the plethora of reasons).

And part of it has to do with the fact that sometimes it’s nice to use a watch for timekeeping, avoiding any potential doom scrolling.

And is there anything more dapper than holding your wrist out to look at your watch? 

Alright — let’s talk about automatic watch accuracy.

Automatic and Mechanical Watches: All About Accuracy

In practice, when you’re looking at an automatic or mechanical watch, you want to consider not just accuracy but precision. And yes, they are two different things, which I also go into in our exploration of the most accurate movements.

Accuracy measures how true the movement is to the UTC or the Coordinated Universal Time. Greenwich Mean Time used to be the universal standard, which is where the term GMT watch comes from. 

Both GMT and UTC are measured against the same standard of true time. The difference is that GMT displays the time zone in Greenwich, England. Coordinated Universal Time is, as its name suggests, a universal display not specific to any time zone.

Precision measures the stability of this accuracy. If a movement is displaying the same accuracy every day, compared to averaging out at the end of the week or month, then it’s perfectly precise. This doesn’t really happen, though.

Accuracy

A movement’s accuracy is usually graded on how many seconds it loses or gains a day, on average. A mechanical watch can deviate as much as gaining or losing 10 seconds a day. 

However, watch brands usually display a pretty wide range in their movement product descriptions (likely to check the expectations of watch wearers).

For example, Seiko advertises the accuracy of their 4R36 movement, common in their modern automatic watches, as minus 35 seconds to plus 45 seconds a day.

However, this is likely a worst-case scenario. Check any watch forum, and you’ll see that wearers of this movement often report better accuracy than this. I’ve personally seen the 4R run at around plus or minus one to five seconds a day.

The positioning of the watch can also make a difference, which I’ll cover momentarily.

Precision

Again, precision is all about stability and consistency.

Suppose movement A is accurate within two seconds. In a given week, let’s say it’s deviating plus a second one day, then minus two the next day, then plus three the day after that, minus one after that, then plus one after that.

Let’s say movement B is also accurate within two seconds. In a given week, it’s consistently switching back and forth. One day, it’s plus two seconds; the next, it’s minus two seconds, then plus two, then minus two, persistently. 

They’re equally as accurate, but B is more precise. Since they’re equal in accuracy, movement B ends up being the more reliable one.

So, in practice, how accurate your automatic watch is depends on its accuracy and precision, all things held constant.

Beat Rate

Precision doesn’t have a grading system the way accuracy does with its plus or minus seconds a day measure. However, a watch’s frequency can give you an idea of a movement’s precision.

Precision is all about stability. Usually the higher the beat rate of a movement, the easier it can recover from shocks, impact, and gravity. Again, this is all things considered, since there are modern solutions to these things these days.

Most high-end watch movements have a beat rate of at least 4 hertz (making it a 4Hz movement). This means it has a 28,800vph, or vibrations per hour, which is the equivalent of 4 oscillations a second, hence the 4Hz qualification. 

What Is the Acceptable Accuracy for an Automatic Watch?

Though Andy Warhol might disagree, what matters most is that you can use your watch to tell time and that you understand it. If you know how much time it loses or gains and how often to wind or service it, you understand its language, so to speak.

A lot of good mechanical watches can deviate within five seconds a day or be as tight as plus or minus three seconds a day.

COSC certification is otherwise known as the stamp of approval by the Contrôle officiel suisse des Chronomètres or the Official Swiss Chronometer Testing Institute. COSC certification is considered a gold standard. 

For certification, this institute requires a movement to stay accurate between minus four and six seconds a day in the face of impact and temperature. If a watch can achieve this, it’s an official Chronometer.

Still, brands like Rolex often go beyond that, achieving Chronometer status. They regularly ensure their modern movements are accurate between plus or minus two seconds.

The acceptable accuracy of your automatic watch depends on what you’re using it for. Besides, few automatic movements will be as accurate as a quartz crystal watch anyway.

Watch Position

Of course, the way your watch is positioned affects the parts of the movement. The influence of gravity is actually the reason why the tourbillon was invented — read all about that here.

In fact, COSC certification not only subjects movements to different tests but also does them in different orientations. This makes sense since watches rarely ever sit in one single position.

Movements often perform their best when facing dial-up or dial-down. This way, it’s horizontally parallel to the floor, which causes less friction among the parts.

It helps to place your watch dial up or down on a flat surface when you aren’t wearing it, which is something you’ll probably just do naturally.

Here’s a quick lesson in official watch terms. There are six watch positions. In addition to face up and face down, we also have:

Crown left:

Crown right:

Crown up:

And crown down:

Got it? 

Conclusion: Does Accuracy Make a Good Watch?

Basically, a qualified watchmaker will adjust a watch so that it’s adjusted to all six positions. 

But in an age where, again, we don’t use watches to tell time all the time, accuracy is just one consideration. After all, if accuracy is the only thing that makes a good watch, then technically, quartz models are better than automatics.

Of course, this isn’t necessarily true.

Are you looking to learn more about accuracy, automatics, and watches in general? Subscribe to our newsletter at The Slenderwrist to get the latest, curated by our watch experts!