Sync My Watch
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The habits that keep a mechanical watch accurate and its date mechanism intact.
Unscrew the crown if it screws down, then pull it all the way out when the seconds hand reaches 12. On most modern movements the seconds hand stops. Set the hands to the next full minute, watch the readout above, and push the crown home the instant the seconds pass :00. Screw it back down.
For hours around midnight the date mechanism is already engaged, and using the quick-set date then can jam it or damage it. The safe habit for any watch: turn the hands until the hour hand points at 6 before touching the date. Manufacturers state the risky hours for their own movements; the widest of the published windows below, , is what this page warns about.
| Movement | Avoid setting the date | Stated in |
|---|
If your movement isn't listed, its manual is the authority. Each row above was checked against the manufacturer's own document; brands whose guides could not be verified are left out rather than guessed.
Set the minute hand a few minutes early, then advance it clockwise onto the mark. That takes up the play in the gear train, so the hand settles exactly where you left it instead of drifting late.
A stopped automatic needs power before it will keep time. Give the crown 20 to 40 turns in the winding position, then set the time. Wearing it will do the rest.
Chronometer-grade movements are rated between −4 and +6 seconds a day by COSC; Rolex's Superlative standard is ±2, and METAS certification allows 0 to +5. Many entry-level automatics run wider. Checking against this page once a week keeps a good watch within a minute.
The red hand points to the hour of your second zone on the 24-hour scale inside the dial: 24 at the top is midnight, 12 at the bottom is noon. Unlike a mechanical GMT watch, it also shows half-hour and 45-minute zones correctly.
Your computer's clock is not used. When the page opens it asks the nearest AWS edge server for the time several times in quick succession, keeps the answer with the shortest round trip, and runs the watch from that moment on using your browser's monotonic clock. The edge servers are kept on time by Amazon's satellite-connected atomic reference clocks.
The status line under the time says which edge answered and how uncertain the answer is: half the round trip plus a small allowance. On a good connection that is a few hundredths of a second, far tighter than a human hand on a crown.
If no server can be reached, the page falls back to this device's clock and says so plainly. Time zones and daylight saving rules come from your browser's built-in database, so they stay right even for places whose rules changed recently.