COSC vs METAS. Precision Standards in Watchmaking

Watchmaking is a blend of art, science and precision. The accuracy of a watch not only defines its functionality, it is also a testament to the craftsmanship and engineering detail behind its manufacture. Two of the most recognised standards in assessing the accuracy of watches are COSC certification and METAS certification.

History of watchmaking certifications

The quest for precision in clocks dates back to the 18th century, during the age of maritime exploration. At that time, navigation relied heavily on the ability to measure time accurately to determine longitude at sea. John Harrison, a self-taught English carpenter and watchmaker, solved this problem with his innovative marine chronometer. This device enabled seafarers to calculate their longitudinal position with unprecedented accuracy, significantly reducing the risk of accidents and loss at sea. Harrison’s invention was the beginning of the era of high-precision timekeeping, laying the foundations for future developments in watchmaking.

With the advancement of technology and the growing demand for personal watches, the focus shifted from marine chronometers to wristwatches. In the early 20th century, the need for standardised testing to ensure the accuracy and reliability of these watches became apparent. In response, organisations such as the Swiss Official Chronometer Control (COSC) were created to establish and maintain rigorous accuracy standards. These tests, in addition to ensuring that the watches functioned correctly in specialised environments, also guaranteed their performance in everyday situations, cementing the reputation of Swiss watchmaking worldwide.

What is COSC (Contrôle Officiel Suisse des Chronomètres)?

Founded in the mid-20th century, the COSC (Contrôle Officiel Suisse des Chronomètres) sets rigorous standards for assessing the accuracy of watches. The COSC certification process involves 15 days of extensive testing in different positions and temperatures. Movements are tested in five positions and at three different temperatures (8°C, 23°C and 38°C). To be certified, a movement must maintain a daily accuracy of between -4 and +6 seconds.

Prestigious brands such as Rolex, Breitling, Tissot and Omega often have their watches tested by the COSC.

What is METAS of the Swiss Federal Institute of Metrology?

The METAS (Swiss Federal Institute of Metrology) standard was introduced in the 21st century to address modern challenges, especially resistance to magnetic fields. With the increasing presence and widespread use of electronic devices in everyday life, watchmakers became more concerned about the effects of magnetic fields generated by these devices.

To obtain METAS certification, a watch must first pass the COSC tests. It then undergoes additional evaluations such as resistance to magnetic fields up to 15,000 gauss, accuracy in various conditions and a water-resistance test. Omega is the main proponent of this certification, having incorporated it into several of its watch lines, other brands such as Tudor also have this certification on some of their watches.

COSC vs METAS comparison

Test procedures

COSC: evaluates the daily accuracy of the watch in different positions and temperatures. It is a detailed process that lasts 15 days and focuses mainly on chronometric accuracy.

METAS: consists of all COSC tests, plus additional evaluations for magnetic resistance, accuracy under exposure to strong magnetic fields and durability in real-life conditions.

Areas of focus

Accuracy

Both standards guarantee high accuracy. While COSC focuses on daily accuracy (-4/+6 seconds per day), METAS goes further, ensuring even higher accuracy and stability under magnetic exposure conditions.

Magnetic resistance

Here, METAS excels significantly, testing the watches’ ability to withstand up to 15,000 gauss, a very important feature these days as everything is full of electronic devices.

Durability

METAS also evaluates water resistance and power reserve, which are vital to the durability and reliability of the watch on a daily basis.

Impact on the watch industry

Both certifications are symbols of excellence in watchmaking, but METAS provides a more comprehensive assessment that responds to today’s needs. The adoption of METAS by Omega and other brands is the result of a growing commitment to innovation and adapting to today’s challenges.

If you are looking for watches with precision certifications in Ideal Joyeros you are in the right place. You will be able to find a wide range of possibilities in our luxury watchmaking section.