Sonotube and Round Column Concrete Calculator
Estimate concrete volume, ready-mix yards, bag quantities, and editable cost for solid or hollow round column forms.
How to use the sonotube concrete calculator
- Measure the actual project. Break irregular work into separate sections and record finished dimensions consistently.
- Enter the core measurements. The quick view focuses on project geometry; add or subtract sections where the calculator supports multiple areas.
- Review purchasing assumptions. Open Advanced inputs to replace example prices, waste, coverage, density, pack size, minimum order, or delivery assumptions with current project information.
- Calculate and verify. Review the formula, limitations, whole-unit rounding, product instructions, and supplier requirements before purchasing.
Key inputs covered: Column section, Form inside diameter, Hollow inside diameter, Concrete height, Identical forms, Placement allowance, Concrete yield per bag, Bag example price, Ready-mix example price.
Result coverage: The sonotube concrete calculator reports 6 separate quantities so the primary estimate and its supporting purchase or planning values can be checked together.
How the estimate works
The circular form area, less an optional hollow core, is multiplied by height and quantity; allowance is added before converting cubic feet to yards and bags.
A solid 18 in diameter form filled 4 ft contains about 7.07 ft3 before allowance.
Assumptions, rounding, and limitations
Dimensions are treated as finished measurements. Only deductions and allowances entered above are included. Decimal measurements display to two places; purchase quantities round up when a whole container or piece is required.
- Use the form's actual inside diameter and the filled concrete height, not its nominal product label alone.
- This tool does not size footings, reinforcement, anchor bolts, columns, piers, or structural connections.
- Follow approved plans, local code, form manufacturer instructions, concrete specifications, bracing, placement-rate, consolidation, and curing requirements.
Sources and review
These references support unit conversions and selected planning assumptions. Product instructions and local requirements control the actual project.
Last reviewed: 2026-10-09
Editorial process
BuildPlanCalc publishes the formula, editable assumptions, limitations, and supporting references so the estimate can be checked rather than treated as a black box. See the calculation and review methodology, or report a correction.
Frequently asked questions
Are the results exact?
No. Results are planning estimates based on the dimensions and assumptions entered. Confirm product coverage, site conditions, and ordering rules with the supplier.