How to Properly Recalibrate Your BatteryAgain, big thanks to Ashtonmore on Reddit for outlining this process. Recalibrating your software battery meter is actually fairly simple, though it takes a bit of time. Proceed at your own risk.
Use your phone until the battery dies. Wait until the screen turns off completely.
Turn your phone back on. It will likely shut down again before it finishes booting, but the battery isn't completely dead yet.
Repeat this process several more times. Power it on, let it keep trying to boot up, then let it die. Eventually, the phone won't even try to boot up anymore — you won't even see the boot logo or splash screen. At this point, you can stop powering the phone back on.
Without turning your phone on, plug it into a charger. Let it sit there plugged in and turned off for at least 6 hours. The goal here is to charge it to 100% capacity without turning the phone on.
Once you're confident that your battery is fully charged, go ahead and turn your phone back on. Resume your normal usage and normal charging habits.
Finally, about a week later, repeat this same process. Let the phone die, try to power it on over and over again until the boot logo doesn't even come up anymore, then charge to 100% without turning it on. Once you've done that, the software battery meter should actually match your battery's physical charge level.