How Automatic Watches Work

An automatic watch has no battery. Its power comes from a coiled spring, and the spring is wound by the movement of your arm through the day. Inside, a few hundred parts turn that stored energy into the steady, sweeping motion of the seconds hand. It is a nineteenth century solution to a problem quartz solved in the 1970s, which is exactly why people still love it: it is a small machine you can wear, and it works without electronics of any kind.

Here is the path the energy takes, from your wrist to the hands.

The five stages of an automatic movement

1. The rotor winds the spring

Turn an automatic over, and if it has a display back you will see a half moon of metal on a central pivot. That is the rotor. It is weighted at the edge, so every movement of your wrist swings it round. Through a set of reduction gears and a ratchet, those swings wind the mainspring a little tighter. Most modern rotors wind in both directions; some only in one.

2. The mainspring stores the energy

The mainspring is a long ribbon of alloy coiled inside a drum called the barrel. As it is wound, it stores energy, and as it slowly uncoils it turns the barrel. When the spring is fully wound, a slipping bridle lets it slide inside the barrel rather than break, which is why you cannot overwind an automatic by wearing it.

3. The gear train passes the energy on

The barrel drives a train of wheels, each turning faster than the one before. One of them turns once an hour and carries the minute hand, another turns once a minute and carries the seconds. Left alone, this train would spin out in a few seconds and empty the spring. Something has to hold it back.

4. The escapement releases it in steps

The escapement does that. A toothed escape wheel at the end of the train is locked and released by a small pallet fork that rocks from side to side. Each rock lets the wheel move one tooth forward, which produces the ticking sound, and gives the fork a tiny push in return.

5. The balance wheel keeps time

The pallet fork is rocked by the balance wheel, a weighted ring attached to a hairspring that swings back and forth at a fixed rate. That rate is the heart of the watch. A common figure on modern movements is 21,600 or 28,800 beats an hour, six or eight beats a second, which is why a mechanical seconds hand sweeps in small steps instead of jumping once a second like quartz.

Price tracker · prices checked October 9, 2026

Price history: Skeleton

What one watch has cost over time, listed and per watch while the store ran its offer.

What the numbers in a spec sheet mean

General figures; each movement's own specification is the reference.

Two of these deserve a comment. Accuracy at this level is modest: a quartz watch might drift a few seconds a month, an affordable automatic a few seconds or more a day, and that is normal rather than a fault. And more jewels does not mean a better watch; past the number needed at the main pivots, extras add little.

Among the established brands, the Seiko 5 Sports ($350) and the Citizen Tsuyosa ($495) are good examples of a sound, widely serviced automatic, and the Tissot PRX Powermatic 80 40mm at $850 is named for its power reserve of up to 80 hours, roughly twice the usual.

Living with an automatic

An automatic worn every day stays wound. One that spends the weekend in a drawer will usually have stopped by Monday. The routine for getting it going again:

1. Wind it by hand if the movement allows, with twenty or thirty turns of the crown in its pushed in position, or give it a gentle shake to start the balance.
2. Pull the crown out to the time setting position and set the hands, moving forward.
3. Set the date last, and never between about 9 at night and 3 in the morning, when the date mechanism is engaged. We explain why in how to set a day date watch.

Keep it away from strong magnets, such as speakers and laptop clasps, since a magnetized hairspring makes a watch run fast. If it suddenly gains minutes a day, that is the usual cause, and a watch shop can demagnetize it in seconds.

Automatic or quartz?

The automatic is not the more accurate or the more practical choice. It is the more interesting one. If you like the idea of a watch that runs on a spring and a swinging wheel, and do not mind setting it after a weekend off the wrist, it rewards you every time you look at the seconds hand. If you want a watch that is always right and never needs attention, buy quartz. Our quartz vs automatic comparison sets out the trade offs in full.

Automatics with an open dial make the case best, because you can watch the balance at work. The Lucky Fours Skeleton at $99.99 shows its movement through a blue openwork dial, and the Spine at $149.99 does the same in an octagonal case. More open dial and closed dial options are compared in automatic watches under $200 and explained in what a skeleton watch is.

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