Question 443730
Assuming you mean 8 ft diameter, and not the circumference:
r = 4 ft = 48 inches
{{{Vol = pi*r^2*h = pi*2304*8}}} cubic inches
{{{Vol = 18432*pi}}} cubic inches
1 gallon = 231 cubic inches
{{{Vol = 18432*pi/231}}} gallons
Vol =~ 250 gallons