Vuosikelloa

Vuosikelloa is a Finnish term that translates to "year clock" or "annual calendar." It refers to a mechanical watch complication that displays the date, day of the week, and month. Unlike a simple date window, a vuosikelloa automatically adjusts for the varying lengths of months, meaning it only requires manual correction once a year, typically on February 29th during a leap year.

The mechanism behind a vuosikelloa is quite complex, involving a series of gears and levers that track the passage of days and months. It requires careful calibration to ensure accuracy over extended periods. Owning a watch with this complication is often seen as a mark of horological appreciation due to its intricate engineering and practical utility. While less common than a perpetual calendar, which accounts for leap years automatically, a vuosikelloa offers a significant step up in convenience from standard date displays. Its presence in a timepiece signifies a higher level of craftsmanship and a dedication to detailed functionality.