3.14*radius^2*length
3.14 [TIMES] (the radius of your pipe)squared [TIMES] the length
or measure straight across the pipe and us that number, the diameter and divide it by 2. In really plain english take the radius (or half the diameter) and square that and then multiply it by 3.14 and then multiply that by the length. So if your radius were 2 and it was 5 long then you would go...
2 squared = 4 X 3.14 = 12.56 X 5 = 62.8 cubic whatever, inches...feet...miles, whatever you measured
Hope this helps
