I'm concerned that I'm not getting near what others are getting.
I wasn't either until today (I got mine on Friday afternoon). Looks like you need to let the battery charge to 100% once or twice so it can calibrate itself.
The same thing has happened to pretty much every iPhone I've ever gotten. Battery life in the first 2 days or so is really concerning, but then it gets dramatically better.
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If you're posting a screenshot of your usage stats, don't forget to say what model you have (6 or 6 Plus)!