Given what? I'll assume given the radius of the pipe (r) and the density of the fluid (p) in compatible units.
GPF = p * PI * r2
Of course, if the units on the density and the radius are not given in gallons per cubic foot and feet you will need to do unit conversions.
31.987 gallons per foot.
375.7952 gallons per foot of 96" pipe
much water per foot will a 5 inch pipe hold
That completely depends on the length of the pipe.
If the pipe is round, with a 55-foot diameter, and 36 inches long, then its capacity is 53,317.3 gallons. If the pipe is round, with a 36-inch diameter, and 55 feet long, then its capacity is 2,908.2 gallons. Either way, we have no way of knowing how much water is in it. For all we know, it may even be empty.
For a 3 foot diameter pipe, 52.9 US gallons per foot of length.
In a pipe with diameter 8 ft, there will be just over 376 US gallons per foot.
0.6528 gallon per foot (rounded)
31.987 gallons per foot.
2.61153 gallons.
A 12 inch diameter round pipe will hold 4.89 UK gallons or 5.88 US gallons per foot.
0.3672 gallon per foot of pipe.
0.212 331 gallons per foot.
375.7952 gallons per foot of 96" pipe
Formula: Cubic feet x 7.48052 = gallons.
11.69
16 gallons