So i usually get multiple readings on my fuel gauge for my 03 RSX. For example; If I get to work, which is about 10miles away, my fuel gauge will read 1/2 a tank, when i get off and im about to head home it'll read less than 1/4. no way i used that much fuel right? But the next morning when i turn the car back on, the gauge will read a little less than 1/2 a tank again..it does this all the time so i can never really tell how much fuel i actually have left..have to keep guessing.

Any ideas on what could cause this issue? I was thinking the fuel tank reader obviously, but any other parts that could contribute to the false reading?