What is the Difference Between Watch Precision vs Accuracy?

What is the Difference Between Watch Precision vs Accuracy? (photo: Niklas Rhose)

Generally speaking, the idea behind wearing a wristwatch is being able to tell the time with a glance at your wrist. While there are many other reasons for choosing to wear a watch, its ability to tell time accurately is of utmost importance. However, there is some confusion regarding the difference between the precision of a watch and its accuracy. Watchmakers test a watch's precision before it leaves the manufacture, but that doesn't necessarily mean it will tell time accurately when it is on your wrist. 

Precision

When watchmakers test precision, they are looking for how close one measurement is to another. For example, when shooting archery, the measure of precision refers to the grouping of the arrows on the target independently of how close those arrows came to the bullseye. Similarly, if a watch measures time with the same variation every day, it is precise, even if it is losing 6 seconds a day. As long as the loss remains at 6 seconds each day, the watch is measuring time precisely, though perhaps not accurately.

Accuracy 

Using the archery example, you can think of accuracy as how close the arrows get to the bullseye. Accuracy is measured against a standard measurement, in the case of watches a measurement of time. So, your watch is only accurate if it tells the right time, even though it can be extremely precise while telling the wrong time every day. There are many factors that can affect the accuracy of your timepiece, including behavioral factors like how much you move your wrist throughout the day and how you store your watch when not in use.

Watchmakers like Rolex publish the precision of their watches after testing them in-house. While the watch may be precise up to -2/+2 seconds per day, that doesn't mean that it will not gain or lose more when on your wrist. However, it is a good indication that the timepiece is capable of keeping accurate time. For more information on how Rolex tests their watches, visit rolex.com. For information on their Superlative Chronometer Certification, check out my post on the subject here.

>>BACK TO FAQ