How to measure Watch accuracy

[nov_revol]

Dear all, am new to this. How do you measure the accuracy of your watch? Do you need to do it over a period of time? Or just 24 hrs will do? When do you need to bring it to recalibrate?

Hope I can learn how to measure accuracy on my non hacking 1601.

Thanks All

[nov_revol]

Thanks, so if it is not within -4/+6sec per day should I be concern? When should I sent in for recalibration? -10sec? Or -15sec? Or maybe leave it?