What's Rolex's accuracy per day?

[Ruprekt]

How much does Rolex allow per day on their watches for it to have a chronometer rating? I know it has to be measured in three positions and all that, but I forget the accuracy per day. I want to say it +/- 10 seconds.

 

[jfazioli]

Superlative chronometer is -4/+6 per day. Rolex isn't the only COSC certified manufacturer though. Some others, like breitling, certify some of their models.

 

[honeybear]

Remember that the COSC certification is of the movement only, before it is cased in the watch. Your actual accuracy on the wrist may deviate from the COSC range of -4/+6 s/day.

 

[Ruprekt]

I have 2 WM9's and one is dead on at 3 seconds slow, the other is about 8 seconds fast per day. I think that's pretty acceptable for a self wound watch.

 

[sanankid]

think about it this way....

8 seconds / 86,400 seconds = 99.999% accurate.

 

[Ruprekt]

True. Nice math!