Leap year calendar
Quantième bissextile | 閏年カレンダー／ウルウドシカレンダー | 闰年日历
Breitling Chrono-Matic 1461 with leap year date © Breitling
The Leap year calendar takes automatically into account months with less than 31 days and of February, when it counts 28 days. It must be adjusted every fourth year.
See Watches with astronomical indications.
See Leap year.