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The Encyclopedia of Horology

Switzerland · Introduced 1996 (Reference 5035), with corresponding patent protection sought by Patek Philippe around the time of launch

Patek Philippe Annual Calendar Mechanism

Partially verified

The 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.

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

Sources & references

  1. Patek Philippe Museum, published history of the annual calendar complication and Reference 5035

Where sources disagree, the disagreement is stated rather than resolved silently.