My battery percentage on my iPhone 4S is stuck?

It's stuck at 60% I've been having this problem since 2 months now and when it shuts off and I charge it again I have to wait till its full charged then turn it off for a while bc if I don't its gonna shut down please help

Use the iPhone until it it shuts OFF itself, due to Low
Battery. Then Charge it back up without interruption,
like unplugging it, to full charge 100%. Then before or
after you do this, Reset iPhone, hold both home and
power buttons until the iPhone restarts itself, ignore the
"slide to power off slider", let the iPhone restart itself.

How long have you had the iphone? If youhave had it for acouple years then its the battery. Its going bad. If its still under warrenty go get it replaced