La Chaux-de-Fonds, February 12, 2026 – Since 1973, the Contrôle Officiel Suisse des Chronomètres (COSC) has been one of the most respected institutions of Swiss watchmaking. As an independent guardian of precision, it has accompanied the rise of Swiss Made by certifying millions of movements and helping establish Switzerland as the world benchmark for horological excellence. Today, on the occasion of the 50th anniversary of the ISO 3159 standard, the COSC opens a new chapter, one that looks firmly toward the future.
An Unchanged Mission, an Expanded Offering
The COSC’s purpose remains the same: to guarantee the precision of Swiss watches through a neutral, independent, and rigorous method. But the life of mechanical watches has evolved over the past half century – greater exposure to magnetic fields, longer power reserves, new materials, and more intensive daily wear.
To accompany this evolution, the COSC is introducing an additional level of certification, an extension, not a replacement, of the existing standard. It will feature a daily rate tolerance of 6 seconds instead of 10, magnetic resistance up to 200 Gauss, and verification of the stated power reserve. In addition, watches will be tested under conditions that closely simulate real-life wear.
The COSC Excellence Chronometer
Today, a certified chronometer movement guarantees precision. Tomorrow, a watch bearing the title “Excellence Chronometer” will commit to performance in three dimensions: tightened precision, anti-magnetic resistance, and confirmed power reserve.
The first level – Certified Chronometer – will continue to exist as a hallmark of performance, while brands will have the opportunity to climb one step higher if they choose. This new distinction adds a new benchmark to the performance hierarchy:
Built on Swiss Made.
Crowned by certification.
Elevated by a higher standard.
A benchmark for competitiveness.
The Method
The new certification builds upon what has defined the COSC’s strength since its inception. For fifteen days, movements are tested according to the seven criteria of the ISO 3159 standard. Once certified as chronometers, they return to the manufacture for casing.
Complete watches then undergo five additional days of evaluation. Using a robot capable of simulating average wrist wear, the watch’s precision is tested under semi-dynamic conditions for 24 hours. This is followed by a measurement where the average daily rate must fall between –2 and +4 seconds per day. Next, the watch is exposed to a 200 Gauss magnetic field while maintaining its performance. Finally, its power reserve is checked to confirm the manufacturer’s stated specifications.
As always, every watch is tested individually. The COSC never relies on sampling. This commitment guarantees the excellence of each certified timepiece.
Steps Toward ImplementationThe transition to the new standard is already underway. Since early 2026, the COSC has been progressively integrating new technologies and strengthening its equipment to measure all criteria of the future label.
In March, the first pilot tests will be conducted in COSC laboratories to validate procedures and support brands through this adjustment phase. In April, attention will turn to the global reveal at Watches and Wonders, where the COSC will present the new certification as part of the LAB projects, a space dedicated to innovation and cutting-edge technologies.
And then? Starting in October 2026, deployment begins: brands will fully enter the new process, and the first watches certified under these redefined standards will start to emerge, a seamlessly orchestrated evolution.
The Future Beats, and COSC Sets the Tempo
“Beyond numbers and protocols, the future is built collectively. By rethinking chronometry standards, the COSC unites the watchmaking industry around a shared ambition: to elevate precision, magnify excellence, and promote Swiss expertise worldwide. To live with one’s time, one must evolve – and to evolve, one must innovate,” said Andreas Wyss, CEO of COSC.