The term accuracy of watches is used to indicate the precision of a watch. The accuracy of a quartz watch is much higher than of a mechanical watch. Let’s have a closer look at the accuracy of the different types of watches:
Accuracy of quartz watches:
The clock generator of a quartz watch is an electronic oscillator. It’s frequency is maintained through a crystal oscillator. The higher the frequency of the used clock generator the higher is the accuracy of the watch. Quartz watches with a quartz of common oscillating frequency usually have a deviation of 15 to 30 seconds per month. Since the deviation is adding up over the months also a quartz watch has to be synchronized on a regular basis.
Accuracy of automatic watches:
Automatic watches are mechanical watches whose clockwork spring is winded up automatically through a rotor with every movement of the arm. The rotor that is usually ball bearing mounted stands still during the movement of the watch case because of its inertia and gravity so that a torsional moment is applied on the clockwork mechanism.
The accuracy of automatic watches depends on different factors. First and foremost the carrying method of the owner influences the accuracy of a watch. With very active persons who a wearing the watch during sports an automatic watch movements react differently from those worn of persons who are sitting most of time behind a desk or in the car. Next to the activity of the owner also factors like temperature and atmospheric pressure play a decisive role. Upscale automatic watches have an accuracy of less than +- 6 sec. per day. A “normal” accuracy is between +- 10-30 sec. per day.
In case a watch has a C.O.S.C (Contrôle Officiel Suisse des Chronomètres) certificate the watch can be labeled as chronometer. Chronometers are with a accuracy of -4 to +6 seconds per day very precise watches.