Automatic Watch Movement Accuracy

Many question the accuracy of automatic watches due to their movements requiring an active wrist to keep ticking. The worry is that self-winding watches may run fast or slow depending on the energy supplied by the wearer, the temperature, magnetic forces and gravity. However, stay tuned we’re ready to explain all the facts…



Do Automatic Watches Gain time?

Technically, yes, automatic watches do gain and lose time yet the amount is so insignificant that it is bound to go unnoticed. Generally, the accuracy of a standard self-winding movement is +-25 seconds per day, so should only gain or lose 25 seconds over two days. Therefore, standard automatic movements are 99.97% accurate.

To find out the exact accuracy, brands usually state the figure proudly in their watch specifications. Many like to share their commitment to precision. Therefore, you should expect the particular watch to run as accurately as is stated. For those who use ETA or Sellita movements it may be worthwhile checking their different grade specifications to understand their accuracy intention. It is time to get your watch checked if it is gaining or losing a significant amount of time. It many need to be regulated. 

If you require a watch with the perfect accuracy a Chronometer is the watch for you offering -4 or +6 seconds per day.

Automatic Watch Accuracy Test

Chronometers are tested and certified to ensure precision. You may have heard of the COSC (Contrôle Officiel Suisse des Chronomèters). It is a non-profit organisation founded to measure, test and certify the accuracy of timepieces. Therefore, if the watch you are looking at has been COSC certified you can rest assured that the timepiece is accurate. This is the highest prestige possible in the watchmaking world. Passing the tests ensures the highest accuracy, which many brands are proud of.

bell-ross-automatic-watch-movementEach will have a unique serial number from COSC engraved on the watch to showcase that the chronometer has passed the 16-day test, surviving under different temperatures and positions. Out of all the automatic watches in the world only 3% of Swiss watches are certified Chronometers costing a lot of money. Think Breitling and TAG Heuer prices. The expense is due to the cost of manufacture to guarantee quality, the time it takes to hand assemble the movement and to be COSC tested. 

There are many chronometers that do claim to have the -4 or +6 seconds accuracy under normal everyday circumstances. The COSC testing is rigorous and extreme however, some non-certified movements can achieve precision in everyday life when taken care of. 

What Is the Best Automatic Watch Position at Night? 

To maintain accuracy overnight it is advised to leave your timepiece lying flat, faced up. This is due to the fact that the watchmaker adjusts the rate when the timepiece is flat. If left on it’s side gravity can pull the hairspring making your watch less accurate. It’s also a good idea to place your timepiece in a watch winder if you own one as it will build up a sufficient power reserve and protect from damage. When deciding on the placement of your watch avoid strong magnetic sources such as stereo speakers and tablets.