Concrete Tube Estimator

A concrete tube is a hollow cylinder. Its concrete cross section is the area of the outer circle minus the area of the inner opening. This estimator squares each diameter, takes their difference, multiplies by pi divided by four, and then multiplies by the tube height or length. Diameters are entered in inches and converted to square feet before multiplication by the length in feet. The resulting cubic feet are also converted to cubic yards for ready-mix ordering. Set the inner diameter to zero when estimating a solid round pier, post footing, or column form. For a pipe, well ring, culvert wall, or other hollow element, measure both finished diameters. Diameter means a straight line through the center, not circumference or radius. Small measurement errors can matter because diameter is squared. Use dimensions that represent the concrete boundaries rather than nominal pipe names unless the manufacturer confirms those names match actual dimensions. The bag estimate assumes one 80-pound bag of premixed concrete yields approximately 0.6 cubic foot. Product yields differ by brand, water content, consolidation, and waste, so read the bag label before purchasing. The ready-mix cost is the exact calculated cubic yards multiplied by the entered unit price. It does not automatically include waste, short-load fees, pumping, reinforcement, forms, excavation, delivery, tax, or finishing. Add an appropriate ordering allowance and compare the result with supplier minimums. This geometry estimate does not design a structural member. Wall thickness, reinforcement, cover, concrete strength, soil support, water pressure, buoyancy, durability, joints, and construction method require project-specific review. Confirm whether the measured length is vertical height or horizontal run and whether end caps, enlarged bases, bells, or penetrations must be calculated separately. For critical columns, retaining structures, wells, or buried pipes, use approved drawings and obtain professional engineering guidance. The calculator is best used to check quantities and compare alternatives before requesting a formal material quote.