If it's just a basic cell phone and not an android cell phone then I've had my battery last for 4 days before needing to charge it again.
Of course the more you use the cell phone the faster the battery will drain.
In my android phone if I'm using it often the battery will drain down in a couple hours before needing charged again and even if I don't use it for a whole day then the battery still needs charging again the next day.
Apps that are updating can cause the phones battery to drain as well.
It's best to just leave your cell phone plugged into the charger when not using it though to keep the battery charged and ready to go.