How accurate is the Apple Watch?

Apple claims the Apple Watch is four times (4x) more accurate than the iPhone. Not only does Apple Watch source time information from 15 different Stratum-1 level time servers around the world, but the device compensates for latency to ensure that every Apple Watch is perfectly synchronized.

Apple Watch hardware includes a crystal temperature-control oscillator, which compensates for exposure to extreme temperatures to reduce drift. The Apple Watch will diverge from Stratum-1 accuracy by 50 milliseconds or less.