How this calculator works
Subtract the inner circular area from the outer circular area and extend the annulus over the tube length and quantity. Waste increases the concrete order and its estimated wet mass. Bags use mixed yield, not density times dry bag mass. The initial 80 lb bag yield is 0.60 ft3; use the package for your product. Finished-piece pricing multiplies tube count only, because a purchased tube already has its final geometry.
Formula
V = pi x (outside diameter^2 - inside diameter^2) x length x quantity / 4; order = V x (1 + waste); wet mass = order x wet density; bags = ceil(order / mixed yield).
Worked example
A 2 m tube with 1 m outside diameter and 0.6 m inside diameter contains 1.00531 m3 concrete. Without waste, its estimated mass at 2400 kg/m3 is 2412.74 kg and volume pricing at $100/m3 gives $100.53.
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Frequently asked questions
Is the volume the liquid capacity inside the tube?
No. It is the material between the inside and outside surfaces. Use pipe volume for the space inside.
Can I enter a solid cylinder?
Yes. Use an inside diameter of zero. The outside diameter and length must remain positive.
Are socket ends included?
No. Bell ends, flanges, reinforcement and changes in wall thickness need a separate takeoff.