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All-day battery life is based on 18 hours with the following use: 90 time checks, 90 notifications, 45 minutes of app use, and a 30-minute workout with music playback from Apple Watch via Bluetooth, over the course of 18 hours.
On its website, Apple says the Watch will take 90 minutes to go from 0% to 80% and 2 1/2 hours to go from 0% to 100%. This charge time was tested by Apple this month using preproduction hardware and software paired with an iPhone running preproduction software.