Gas gauge inaccurate???

I'm not really worried about it at all. But my maverick can be on 1/4 tank, I put $25 in it and the needle goes up as far as the gauge allows. The pump doesn't stop like its full but the gauge shows its way past full. Any ideas how to check this and make sure its accurate? I'm starting to wonder if the sending unit is off or something and this car may not be as bad on gas as I think I'm curious as to how much gas is really in it and if the guage's needle is like "offset", I don't know haha.

Justin the only way to check it is to drop the tank and ohm the sending unit out and check it by moving the unit up and down it sounds like your sending unit is bad