Excel formula for converting tank volume in inches to gallons

[sethrose]

I need the correct formula for converting height in inches to gallons in a tank:
Horizontal tank 96" in diameter and 192" in length which has a 6016.2 gallon capacity. It is a cylinder with flat ends. The formula I have is:

=(((4/3)*(K4^2)*(SQRT((96/K4)-0.608))*192)/231) [K4 is the height in inches]

This formula works for small numbers but as the inches get larger the result is off when compared to a tank chart.

Any help would be much appreciated!!

 

[sethrose]

Awesome!! That works perfectly and the results match the paper chart exactly.
Thanks!

 

[sethrose]

sebek007, I wonder if you would be kind enough to give me the formula for 2 other tanks of the same type but different sizes: The 6000 gal tank formula works perfectly.

2005.4 gallons 8' diameter, 5'4 length
4010.8 gallons 8' diameter, 10'8" length

Thanks!!