Hacking Seconds Explained


Historiador close-up

Most modern wristwatches offer “hacking seconds.” The term refers to the ability to pull out the crown to stop the second hand, then push the crown back in to restart the second hand. With a watch so equipped you can synchronize your watch to an accurate timekeeping source – to the second or better. Before we explore the why and the precise how, here’s the technical bit . . .

Hacking Seconds – Hard Stop

NOMOS hacking seconds stop

On a mechanical watch with hacking seconds, pulling out the crown puts a brake on – or a lever over – the balance wheel (the device that regulates the power coming from the coiled mainspring).

Pushing the crown back in releases the brake or lever, so the balance wheel can go back to doing its thing. The second hand resumes its journey around the watch dial.

If you’re hacking a quartz watch, pulling out the crown interrupts the circuit sending motivational power to the hands. Pushing it back in restores the flow of electrons, putting your battery-powered watch back online.

Perfectionists of the World Unite! Your Time is at Hand!

Mondaine crown

You might want to sync your watch to the second because you’re Swiss or OCD (same thing). More likely, you want to see if your watch is running “properly” (within specifications).

How to Use Hacking Seconds

As I said at the top of the post, you pull out the crown to stop the second hand, then push it back in NSYNC with a reference source.

Like marriage, setting a watch with hacking seconds is a process. Like marriage, there are a lot of ways it can go wrong. Here’s a step-by-step guide (to hacking seconds).

1. Pull out the Crown

OMEGA crown 2

If your watch is water resistant, you’ll need to unscrew the crown before you can pull it out to wind, hack or adjust anything. Press the crown in and turn it counterclockwise until it pops free.

Pull out the crown by prying it away from the case with your fingernail. Watch crowns can be stubborn little bastards. You may have to pry or maybe even pull the crown hard.

Your watch crown may have multiple detents/positions for various functions (e.g., winding, hacking seconds, time and date). Selecting the right detent can be a challenge. Find out where the hacking seconds position lives on your watch either by experimentation or RTFM.

2. Wind the watch

Hacking seconds - OMEGA Aqua Terra

If you have a manual wind watch, find the right detent (usually the first) and manually wind it, placing a finger underneath the crown and sliding it back and forth.

If you have an automatic (self-winding) watch, you may be able to manually wind it. Check your user’s manual or experiment. If it feels like it’s winding, it is.

If you can’t wind your automatic watch and it’s not ticking, wear it for 30 minutes or so, moving around. That will wind your watch sufficiently to “hack” the time.

2. Find a suitable reference source

Hacking seconds reference - HoDinkee time app

You want to set your watch to a source synced to the atomic clock (it doesn’t get any better than that). I recommend either time.gov or the “Time” function on the HoDinkee app (above).

2. Practice

Ideally, you want to stop the second hand exactly at the 12 o’ clock position. That can be a bit like throwing a dart into the bull. Be patient.

Also practice pushing the crown back in. There may be a fraction of a second delay before the second hand starts up. In that case, you’ll have to anticipate the moment when your reference source’s second hand hits 12 ‘o clock or displays 00.00.

3. Set Your Watch Ahead of the Reference Time

Use the appropriate detents to set the hour and date. Then set the minute hand ahead of the reference time. Then hack (stop) the seconds hand. [Note: never set the date when the time is between 10 and 2 or something expensive may happen.]

4. Hack! But Don’t Get Frustrated

NOMOS time 2

If you miss your mark by a second or two, you’ll want to go back Jack and do it again. Reset the minute hand ahead of the reference source, stop the second hand at the exact right point and try again.

When you’re done, don’t forget to screw the crown back into the case – although some watches crowns don’t screw in and remain proud of the case.

Check Your Accuracy

Yema Flygraf Timegrapher

By using hacking seconds to set your watch precisely, you can check your watch against a reference source to know how it’s performing. As accuracy is measured in seconds gained or lost per day, let your watch run at least a day before eyeballing its accuracy.

If you don’t give a damn about split-second synchronization, don’t want to be known as a hacker, but still want to know if your mechanical watch is running accurately (and powerfully) buy a Timegrapher (no commission on link). They’re inexpensive, easy to use and far more accurate than eyeballing.

Now what?

Korman Jewelers service

Now you’ll never be a moment late!

If your mechanical watch isn’t keeping time within manufacturer’s posted specifications – how far outside those specs you consider tolerable is up to you – send it to the manufacturer/authorized dealer or take it to a professional for professional adjustment.

If a quartz-powered timepiece is significantly outside of spec, replacing the battery is your first move. If new juice doesn’t work, the watch needs to go back from whence it came.

Next? Wear/Wind Your Watch Forever Or . . .

Seiko Astron

If this is all too much, there are quartz watches that sync automatically via satellite (e.g. the Seiko Astron). Not to mention smartwatches that sync to your phone or cellular system without significant human intervention, and stay synched forevermore.

Some watch enthusiasts embrace this hacking seconds process – it challenges their dexterity and connects them to their watch in a visceral way. That’s their story and they’re sticking with it. I wonder what you make of the process . . .


  1. I grew up with war and espionage dramas that loved the tropes of exact countdowns, synchronized strikes, etc. Even teen comedy Parker Lewis had the recurring “synchronize Swatches” gag. But I quickly learned that the teacher didn’t care about any time but the one on the wall and contesting it was pointless. Much of my life was of a Cartier tank mindset: I’m not a nurse taking pulses so seconds don’t matter.

    But the old “entertainment center” killed all that. Just as jeweler watch displays tend to set all the watches to the same static time so, you know, they don’t all look like they’re all keeping different time, once televisions and VCR’s made it so two or more different digital time displays were visible together, this error needed correction to avoid being a constant annoyance. Any discrepancy between them was unbearable.

    Once I had a few watches, it became a thing to note that every month or so the minutes were out of agreement and to align them to some reference. But then the damned cellular telephones got second displays. Suddenly everyone had a seemingly indisputable uniform time always at hand, and there was no debate about whether one was actually late for the meeting or not. Exact minute and seconds mattered once again.

    Of course the synchronization takes at least a couple minutes for each time piece, so I still only do it every few weeks. But then I’m a quartz fan, so I don’t need to do it much more. But I recently discovered that the reference time on the computer clock and the cell phone were many seconds apart. My world was shattered. What was real anymore?

    I was going to goof on this Hodinky app and the tenths of a second. But then I remembered this issue of the hourly chime of my Casio and cell phone app slowly diverging from unison to a full second or more apart. I feel I’m setting myself up for unhappiness with this. The price of the joy of seeing a bunch of watches running with the second hands all parallel to one another is getting perturbed when entropy inevitably disrupts this. But at least I know that others have this mania.

  2. It’s a waste of time (sic) to set a mechanical watch to exact time unless you intend to do it every day unless your being paid by the second of course. Otherwise it’s just a toy.

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