Complication · Calendar & astronomy
Day-Date
Partially verifiedA calendar display combining a numerical date with a spelled-out day-of-the-week indication, typically shown side by side or in a double aperture at the top of the dial.
Definition
A calendar display combining a numerical date with a spelled-out day-of-the-week indication, typically shown side by side or in a double aperture at the top of the dial.
Historical origin
Rolex is widely credited with popularising the wristwatch 'Day-Date' layout from 1956, though simpler day-and-date pocket watch calendars predate this by well over a century.
How it works
A day disc, printed with the names of the week (often in multiple languages on rotating discs in some designs), is advanced once every 24 hours by its own jumper and finger, working in parallel with, but mechanically separate from, the date ring.
Because the day disc only has seven positions, its jumper and spring geometry differ from the 31-position date ring, so the two are driven by separate cams timed to change together at midnight.
In simple-calendar day-date watches, the day (like the date) requires manual advancing during short months, since the mechanism has no month-length logic of its own.
Pocket watch context
Day-and-date pocket watch calendars were produced from the eighteenth and nineteenth centuries, often within a triple calendar (day, date, month) layout alongside moon phase.
Wristwatch context
A widely produced wristwatch layout, ranging from simple two-window day-date modules added to a base calibre to fully integrated high-grade movements.
Identification
- Separate day-of-week and numerical date apertures, both changing at (or near) midnight
- On lower-grade movements the day and date may change independently rather than simultaneously if not correctly serviced
Servicing notes
Multi-language day discs and their correctors are calibre-specific and easily damaged by forcing the corrector during the change window; service should be left to a watchmaker.
General guidance only. Complicated mechanisms should be assessed and serviced by a qualified watchmaker or clockmaker specialist, not adjusted at home.
Photographs
Photographs are illustrative examples of the type, not necessarily the exact object described. Verify details against the source file page.
Sources & references
- Rolex company history regarding the 1956 Day-Date wristwatch, treated here as a manufacturer claim rather than independently verified priority
Where sources disagree, the disagreement is stated rather than resolved silently.