The Federal Institute of Metrology METAS publishes what its watch certification covers: "The accuracy of the chronometer under various influencing factors (temperatures, positions, magnetisation, used power reserve); the validation of the power reserve; the water resistance of the watches."
The rate requirement, as METAS words it, is that a watch "must reach a rate accuracy of 0 to +5 seconds per day, i.e. it must never slow down and not be more than five seconds ahead of the actual time".
METAS also certifies mechanical watches as "resistant to magnetic fields of 1.5 T (15,000 G)," a far higher field than the everyday exposure covered by ISO 764.
The governing document is METAS-N001, Requirements for the certification of movements and mechanical watches. Its contents are not quoted here: the document could not be retrieved, so no clause-level detail, test-day count or per-criterion limit is attributed to it.
Sources
Every statement above traces to one of these. Read on the date shown.
- Tier 1 Federal Institute of Metrology METAS, "Watch certification", source read 2026-09-26