Help with fuel guage PLEASE!

I just refilled the tank after my OEM NOS sender (04051004 latest replacement number from Mopar) installation. Gauge read a needles width over 1/4 tank, put 13.48 gallons in to the tank to make it full. 0.25 x 18 = 4.5, 18 - 4.5 = 13.5 I think my gauge is accurate enough! (I only got 17.5 gallons into the tank from siphon hose empty and the tank has a crushed area. Assuming 17.5 = max tank will hold 0.25 x 17.5 = 4.375, 18 - 4.375 = 13.625. ) All of the values are within 1% I'm good! Not bragging just VERY happy with my NOS sender!