How Does an Automatic Watch Work? (Ask an Effortless Gent)

by Karlton Miko Tyack  |  in Watches

The watch community’s love for automatics is an interesting phenomenon. After all, quartz watches are perfectly respectable and more accurate. Few utilitarian accessories have survived, and thrived, for simply being the cooler option. 

If you’re an automatic watch fan, you’re likely a horologically curious person. We’re gonna ease your curiosity today and explain exactly how an automatic watch works.

image by Danil Shostak

What’s the Difference Between An Automatic, Mechanical, and Quartz Watch?

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An automatic movement is a type of mechanical movement. Unlike a watch with a quartz movement which is powered by a battery, mechanical movements rely on a spring-driven mechanism.

Automatics are also called self-winding watches. As an at-a-glance explanation of how automatics work, these special timepieces feature a rotor which spins every time you move your wrist. That motion powers the watch’s mainspring, which then winds the watch automatically. Non-automatic mechanicals need to be manually wound.

You can tell the difference between a quartz movement and a mechanical movement based on the watch’s second hand. A quartz second hand ticks, while a mechanical second hand sweeps.

The Fundamental Parts of an Automatic Watch

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These are the parts that every automatic watch needs to run, complications aside.


The mainspring is a metal spiral which stores the watch’s power when it’s wound and tightened. As the mainspring unwinds, the force of its retraction, or untightening, turns the wheels of the watch thus powering it.

Think of the mainspring as the watch’s power plant. For example, Rolex’s 3255 movement features a longer mainspring than its other movements. This means it will take longer to retract. This is why it has a longer power reserve at 70 hours.

Rotor/Oscillating weight

The oscillating weight is the semicircular central weight that makes automatic watches automatic. As you move your arm, the weight moves back and forth like a swing, and winds the mainspring so you don’t have to do it manually.

close-up of rotor

Balance wheel and hairspring

In an automatic watch, the balance wheel is the equivalent of a pendulum in a grandfather clock. It’s a weight that rotates back and forth, perpetually brought back to the center position by the hairspring or balance spring.

This oscillation is impervious to outside movement. The balance wheel and hairspring are the watch’s regulator and its time-keeping element.

Escapement and Gear Train

The escapement is a mechanical linkage consisting of an escape wheel with “teeth” and a pallet. It stimulates the balance wheel and unfastens the gear train, which causes the watch’s hands to move. 

The escapement is what stops the wheels in the watch from spinning out of control. With each swing of the balance wheel, just one “tooth” of the escapement wheel is released, the rest of the escapement wheel held back by the pallet. This allows the gear train to advance, and thus the watch hands to move by an incremental amount.

The gear train is made up, usually, of four different wheels including the escape wheel. Again, every time the gear train is released, the watch hands move.

The center wheel moves once an hour and powers the hour hand, the second wheel moves every second powering the second hand, and the third wheel moves once per minute powering, you guessed it, the minute hand.


This mechanism transfers the energy from your motion to the mainspring. It’s called a reverser mechanism because regardless of which way the mainspring is turning, the reverser allows the rotor to wind it properly. Your energy is transferred through a series of gears.


Jewels are synthetic rubies placed in high-friction areas of the watch to prevent these parts from wearing out. For example, a jewel is placed in the center of the wheel because it’s constantly turning.

Alright, now let’s put it all together!

How an Automatic Watch Works

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Let’s say you’re wearing your fully-wound automatic watch around town.

Your wrist movements stimulate the rotor which then winds the mainspring, the watch’s power plant.

The mainspring’s energy then transfers through the gear train’s wheels into the escapement.

The escapement then sends incremental impulses to the balance wheel, the watch’s timekeeping element. The balance wheel’s oscillations are maintained by the escapement.

Remember, each swing of the balance wheel releases just one tooth of the escapement wheel, the rest of the wheel held back by the pallet, keeping the wheels from spinning out of control.

Balance Wheel, Hairspring and Ruby Impulse Roller Jewel

Each swing of the balance wheel moves the wheels of the gear train, thus moving the watch’s hands.

By this point in the process, the power still originates from the mainspring. And of course, if you perpetually wear your mechanical watch, it stays powered up!

How Long Do Automatic Watches Last?

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Automatic watches are meant to last forever. Since it’s mechanical, any malfunctioning part can be serviced or replaced. Short of smashing it into pieces, there’s always a way to “switch back on.”

An important question to ask yourself: If my mechanical watch costs $200, and servicing it or fixing a malfunction will cost anywhere from $50 to $300, should I just get a new one? Save for sentimental value, it’ll be more cost-efficient to do the latter.

Fortunately, excellent automatics, for example the Orient Ray II and Orient Mako II, can last anywhere from five to seven years without servicing. Even if you choose to retire them at that point, they will have served their purpose.

High-quality automatics like Rolex watches feature COSC-certified movements, with premium finishes and up to 28,800 beats per second. These watches will often always be worth resuscitating -if it ever even gets to that!

Do You Have to Wear an Automatic Watch Everyday?

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Letting your automatic watch stop doesn’t harm it, so you don’t have to wear your watch everyday. If it stops you’ll simply wind it up again.

Maintaining the energy in the mainspring does allow for a continuous and accurate display of time though. If this is important to you, consider a watch winder!

Is an Automatic Watch Worth It?

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watch is just a little different than the other. And, of course, even the most innovative of technologies can’t replace art. 

On that same analogy, buying a luxury, legendary automatic watch (a Submariner or a Speedmaster for example), is like buying an important piece of art. If feeling like part of their lore is important to you, then it’s worth it. 

To you, what’s the difference between say a prewar home with history and character that’s built by a foremost architect versus a brand new awesome home with amazing, practical smart house technology? Figuring out whether or not an automatic watch is worth it to you is along those lines.

close-up of automatic movement mechanism

Not that important quartz watches don’t exist. After all, Timex is a heritage American brand with excellent quartz timepieces and the quartz Omega Seamaster 300 has plenty of Bond credibility. Automatics have just been around longer.

The first self-winding watch was invented by Abraham-Louis Perrelet, a Swiss horologist in Le Locle in 1776. Another Abraham Louis, surname Breguet (yes, that Breguet), made further strides in fashioning a self-winding mechanism in 1777, and in 1778 Belgian watchmaker Hubert Sarton put a rotor in it.

Finally, English watchmaker John Harwood created a wristwatch that uses kinetic energy for power in 1922. A decade later, Rolex introduced the Oyster Perpetual

What Are the Best Automatic Watches

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Of course anything certified by the COSC means you’ll be getting something complex and precise. At the end of the day though, any automatic watch really is a remarkable little machine. Whichever timepiece you truly love, based on your budget and tastes, is the best automatic watch for you!

We hope this was helpful in helping you learn more about how an automatic watch works!