Accuracy in watchmaking has always been something of a losing battle for mechanical watchmakers. The humble quartz watch settled that debate decades ago, leaving luxury mechanical watches to compete in areas like craftsmanship, heritage, and emotional appeal rather than pure precision. Grand Seiko, however, has never been content with this arrangement. With their latest release at Watches & Wonders 2025, the Japanese brand has fundamentally redefined what accuracy means for a mechanically-powered timepiece—while simultaneously addressing one of their most persistent customer complaints.

Let’s start with the headline: Grand Seiko’s new Spring Drive Caliber 9RB2 boasts an accuracy rating of ±20 seconds per year. Not per day. Not per month. Per YEAR.

To put that in perspective, a standard COSC-certified chronometer is rated at -4/+6 seconds per day, which translates to roughly ±150-180 seconds per month or roughly ±1,800-2,200 seconds per year. Even Grand Seiko’s previous Spring Drive movements, with their impressive ±15 seconds per month accuracy, would drift up to ±180 seconds in a year’s time. This new U.F.A. (Ultra Fine Accuracy) movement improves on that by a factor of nine.

This achievement is a case of Grand Seiko doing what they do best—quietly pushing the technical boundaries of watchmaking while everyone else is distracted by marketing hype. The U.F.A. designation harkens back to the brand’s V.F.A. (Very Fine Adjusted) watches from 1969 to 1975, which were legendary for their precision. It’s a fitting tribute that underscores Grand Seiko’s unwavering pursuit of performance excellence over more than six decades.