Question: how to work out how much concrete for a round hole?
Answer: Choose Round Column (or Round Slab) on the calculator.
Enter Height 4 ft (or 48 in)
Enter Diameter 10 in.
Calculate and the answer is 0.08 cubic yards for one concrete tube.
Multiply 0.08 x 50 = 4 total cubic yards of concrete for 50 tubes.