Switzerland · Introduced 1996 (Reference 5035), with corresponding patent protection sought by Patek Philippe around the time of launch
Patek Philippe Annual Calendar Mechanism
Partially verifiedThe annual calendar created a durable new complication category adopted industry-wide, offering much of the everyday convenience of a perpetual calendar at a fraction of the mechanical complexity and cost, and it remains a staple complication across many manufacturers.
The annual calendar mechanism automatically accounts for months of 30 and 31 days (requiring correction only at the February/March transition each year), sitting in complexity and cost between a simple date display and a full perpetual calendar.
Patek Philippe introduced the complication commercially with the Reference 5035 in 1996, and the mechanism's date-carry logic was protected by the company's own patent filings around the launch date.
Background
An annual calendar in the context of horology is a mechanical watch feature that displays the hour, day, date and month. It automatically adjusts for months containing 30 or 31 days. A manual correction is necessary once per year, typically on the first of March, to account for the February transition. This system serves as a less complex and less expensive alternative to the perpetual calendar mechanism.
Patek Philippe introduced the first annual calendar indicator designed for a wristwatch in 1996. The complication was patented by the company at the time of its debut. It is currently utilized by various watchmaking companies within the industry.
Written from the encyclopedia entries listed under Sources; each statement was checked against the cited text.
How to verify this yourself
Confirm the specific Swiss and/or international patent filing details directly against the Swiss Federal Institute of Intellectual Property and World Intellectual Property Organization registers under Patek Philippe's name and the 1995–1996 filing window, rather than relying on marketing-history summaries alone.
Manufacturers known to have used it
- Patek Philippe
- numerous other manufacturers under independently developed, non-infringing annual-calendar mechanisms following Patek's patent term
Photographs
Photographs are illustrative examples of the type, not necessarily the exact object described. Verify details against the source file page.
Sources & references
- Annual calendar, Wikipedia (English), retrieved 2026-10-28 (text CC BY-SA 4.0)
- Patek Philippe Museum, published history of the annual calendar complication and Reference 5035
Where sources disagree, the disagreement is stated rather than resolved silently.