An Annual Calendar is a watch complication that automatically adjusts the date for months with 30 or 31 days, requiring manual correction only once a year at the end of February.
An annual calendar automatically accounts for months of 30 and 31 days, requiring just one manual correction per year—at the end of February, which has 28 or 29 days. Regular date watches need correction 7 times per year (after each short month). Invented by Patek Philippe in 1996 (reference 5035), the annual calendar sits between a simple date display and the fully perpetual calendar in complexity and price.
A perpetual calendar knows the complete Gregorian calendar including February's variable length and leap years, requiring no corrections until 2100 (when the calendar skips a leap year). An annual calendar recognizes 30 vs 31-day months but not February's irregularity, requiring one correction each March 1st. Perpetual calendars are significantly more complex (adding another 100+ parts) and considerably more expensive—Patek's basic perpetual calendar references command 5-10x the price of comparable annual calendar models.
Patek Philippe invented and trademarked the modern annual calendar mechanism, making it a signature complication in references like the 5396 and 5205. IWC produces several annual calendar models including the Portugieser Annual Calendar. A. Lange & Söhne offers an annual calendar in their Saxonia collection. Rolex does not make annual or perpetual calendars. Other notable annual calendar makers include Omega, Jaeger-LeCoultre, and Breitling across various price points.