Why won't my iPhone 5s charge to 100%?

My new iPhone 5s will not charge all the way to 100% even after leaving it on the charger all night. Is there any explanation for why this is?
And is this something I should worry about? Is this evidence that my battery might die early?

(Please excuse the infinite screenshot picture., I was having a bit of fun.
I just took a screenshot to show you the battery life.)

There may be something wrong with your battery and although its not a big deal, I would still get it checked out. Before you actually go to an apple store, I would recommend you to restore it as "new" through iTunes. If restoring it doesn't fix the issue, then there might be something wrong with your phone physically. This is when you should go to apple. Most likely, they'll replace the phone for you.

  • Why won't my iphone 8 plus charge to 100 percent and stays at 98 percent? I don't leave it all night charging. I always wake up around 7 then charge it for like 2 or 3 hours and it will stay at 98 percent, but when I restart it, it would go to 100. And I just recently bought it. Why is this problem?
  • What will happen if I didn't charge my new iPhone 5 to 100%? Will it affect my phones battery life? Some people say you should charge it 'til it reaches 100.
  • Should I let my iPhone trickle charge at 100%? Some websites and apps are saying you should let your battery trickle charge at 100%, which means the percentage might say 100% but the unplug symbol isn't there yet, should I wait for that symbol to be there even though it's at 100%?
  • My iPhone 5s won't charge to 100%? I got my iPhone 5s last Christmas (so it's not even a year old yet) and I've taken good care of it but it won't charge to 100% anymore, even overnight. If I leave it on overnight, it'll just charge to 99%. I thought the cable was the problem so I bought a new cable but that didn't fix the problem so I'm assuming its the phone. Any ideas? Would Apple replace it if I took it to them? Any other information will be greatly appreciated.