Annual calendar vs perpetual calendar
An annual calendar needs one correction a year; a perpetual needs none until 2100. How they differ, what each costs to own, and how to set each one.
Published
The difference
- A simple date needs correcting after every month shorter than 31 days: five times a year.
- An annual calendar knows the 30- and 31-day months. It only needs correcting once a year, on 1 March, because it treats February as 30 days.
- A perpetual calendar also knows February and leap years. It needs no correction until 1 March 2100, which is not a leap year.
What they show
Both usually show the date, day and month. A perpetual adds a leap-year indicator, and many of each add a moonphase. The perpetual calendar helper shows what every hand should read today.
Which one?
- An annual calendar gives most of the convenience for a fraction of the price, and it is simpler to service.
- A perpetual calendar is a high complication. It costs much more, and takes more care to set if it stops.
- Either way, keep it running: on the wrist or on a winder.
Setting them
The one correction an annual calendar needs: on 1 March it shows the 29th, or the 30th in a leap year. Press the date corrector until it shows the 1st, outside the danger window. On many annual calendars the month moves on with it. For a perpetual that has stopped, follow the perpetual calendar guide.