Chronometer — COSC Certified

Movements held to the standard of an independent Swiss institute, tested across positions and temperatures. Certification is a quiet promise, kept daily on the wrist. Precision, verified and then set aside to simply work.

What COSC certification means

COSC (Contrôle Officiel Suisse des Chronomètres) tests each movement for 15 days in five positions and three temperatures. To pass, an automatic movement must keep an average daily rate within −4 to +6 seconds. Hour II of the ChronoSeasons dial, part of the Boardroom season.

How to choose

The Tissot Ballade Powermatic 80 COSC is one of the most accessible ways to own a certified Swiss chronometer, with an 80-hour power reserve and an anti-magnetic Nivachron balance spring.

Read the full guide: COSC-certified watches explained — and the most affordable way in.