Battery life was one of the biggest questions we expected Apple to answer in today’s keynote about Apple Watch. The official figure given by Tim Cook on stage was “about 18 hours”, which is roughly in line with what most people expected. But battery life, of course, will vary heavily depending on your usage pattern. To give us an idea of the kind of battery life we can expect in several common scenarios, Apple has set up an official battery life info page for Apple Watch. The numbers are solid all around, but I found this bit to be particularly interesting/useful:

If your battery gets too low, Apple Watch automatically switches into Power Reserve mode so you can continue to see the time for up to 72 hours. Testing conducted by Apple in March 2015 using preproduction Apple Watch and software with 4 time checks (4 seconds each) per hour. Battery life varies by use, configuration, and many other factors; actual results will vary.

It’s so simple, but I think this will be one of the most useful features in everyday use. Personally, it’s not uncommon for me at all to have my iPhone die on me if I arrive home a little later than usual, not to mention if I go out at night. Apple Watch will be no different in this regard, but it’s good to know that even if your battery dies and you can’t use any of its fancy features, at least your watch will continue to tell the time.

Knowing the exact time you made it home last night is important, if only just so you can feel the appropriate amount of guilt and remorse about it in the morning. It’s the little things.