COSC

Contrôle Officiel Suisse des Chronomètres (COSC). The universally recognized,
independent label that certifies
Swiss watchmaking excellence.

Founded in 1973, the Contrôle Officiel Suisse des Chronomètres (COSC) is the universally recognized, independent official Swiss chronometer testing organization. It ensures that only the most precise timepieces earn the coveted chronometer certification. Our mission is simple yet uncompromising: certify the excellence of Swiss watchmaking by upholding the highest standards of precision. Through ou

r expertise, we provide brands with a mark of credibility and consumers with the assurance that their timepiece is engineered for accuracy. The COSC, a proud partner of all those who promote Swiss watchmaking excellence.

08/07/2026

Did you know?

Before reaching your wrist, every COSC movement undergoes an uncompromisingly rigorous protocol.

White dial⚪, two model dots, black hands⚫: these markers enable ultra-precise optical measurement, calibrated against the ultimate time reference: the atomic clock.

26/06/2026

When rigorous testing is the guarantor of precision.
Every day, thousands of movements and watches pass through our laboratories.

20/06/2026

✨ Inauguration de l’exposition « Des étoiles aux atomes » ✨

Le temps d’une découverte, plongez au cœur de la haute précision au Château des Monts, au Locle.

Le COSC est fier d’avoir soutenu ce magnifique projet, qui met en lumière la quête d’excellence, de précision et d’innovation qui nous anime.

Nous invitons tous les passionnés, curieux et amoureux de science, de savoir-faire et de découvertes à venir explorer cette exposition à partir du 21 juin. Une expérience à ne pas manquer!

18/06/2026

Trusted by the industry. Proven by performance.
Discover our Annual Report and explore the full set of figures on our website.

17/06/2026

Not all timepieces are created equal or certified equally.

At COSC, four distinct types of timekeeping instruments can earn chronometer certification:
🕰️ Mechanical wristwatches
🔋 Quartz wristwatches
🧭 Pocket watches
📍 Fixed-position timepieces (like table clocks)
Four categories. One standard of excellence.

The details? You’ll find all the details on our website in our bio.

09/06/2026

More than just a Swiss watch: precision and performance certified by a neutral organization: the COSC

19/04/2026

Today at the COSC booth: discover precision up close.

15/04/2026

A few milimeters can make all the difference. Test your dexterity and come and regulate a movement at the COSC booth in the Watches and Wonder Lab.

14/04/2026

Is your Watch truly precise? Come and test it, discover what influence its reliability and explore the secret behind COSC certification at the Watches & Wonders LAB

02/04/2026

Ready to put on your lab coat for an immersive experience at the Watches & Wonders LAB? Come test your watch, regulate a movement, and dive deep into the world of COSC certifications.

Adresse

Avenue Léopold-Robert 65
La Chaux-de-Fonds
2300

Téléphone

+41329138078

Site Web

http://www.cosc.swiss/

Notifications

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