If you own a Pixel and you've noticed that your battery life estimates have gotten more accurate in the past few days, that's not a coincidence. A Google product manager made an announcement yesterday regarding the new, smarter way that your Pixel will calculate your remaining battery life.
Pixels would previously make simple (and often incorrect) estimations on your usage. For instance, if you'd been using about 10% of your battery every hour for the past few hours, your phone would assume that you'd continue to use 10% of your battery every hour for its calculation. But now, your phone uses an on-device model based on usage from similar days or times of day to create more accurate estimations of your usage.
To see your new, more accurate battery life estimate, navigate to the Battery section in Settings and the hours remaining will be right there. To get a more accurate view, you can tap the battery icon and see a graph (notice how it's curved to reflect your own usage). As far as we can tell, this was already built into the Pixel 2 and Pixel 2 XL from launch, so it should be new only to the first-generation Pixel devices.
- Google Support