Fuel Gauge Question

Or you could do what I did... With an empty tank, add 1 or 2 gallons at a time, and record the readings on the gauge. I found out exactly how much my tank held (16.5 gallons), and how much is in the tank at various gauge readings. 4 gallons: right on the E line, 7 gallons: between 1/4 and E, 10 gallons: just over 1/4, 12 gallons: just under 1/2, 14 gallons: just below the F line, 16.5 gallons: right on the F line. Crazy stuff.