Side-by-side comparison of chronometer certification standards — not beat-rate math.
COSC focuses on independent timing certification. METAS Master Chronometer-style testing is broader and may include magnetism and practical performance tests. In-house chronometer claims vary by brand and must be read carefully.
| Standard | Focus | Good to know |
|---|---|---|
| COSC | Independent timing certification | Classic chronometer reference |
| METAS-style | Broader practical testing | Often includes magnetism-related tests |
| In-house | Brand-defined standard | Quality varies with the brand’s rules |
• Accuracy after years without service
• Immunity to magnetism in daily life forever
• Perfect rate in every wearing position forever
• That a fake dial word equals real certification
What is the difference between COSC and METAS? COSC is classic independent timing; METAS-style testing is broader and more practical in many cases.
Is an in-house chronometer the same as COSC? Not necessarily.
Does chronometer certification guarantee lifelong accuracy? No.
Which chronometer standard is best? Depends on whether you value independent timing, broader testing, or brand-specific rules.