Concrete Estimator - Tube

How to use this concrete tube calculator

What this calculator does

This tool estimates the concrete needed for hollow cylindrical forms such as tube footings, pipe collars, round formwork, protective sleeves, and similar annular sections. It calculates the net geometric volume, multiplies that volume by material density to estimate weight, applies a waste allowance, rounds the required premix bags up to a whole number, and optionally estimates cost. It is a quantity-planning aid, not a structural design check: it does not determine wall reinforcement, bearing capacity, concrete strength, curing time, or code compliance.

When to use it

Use it when ordering bagged concrete for one or more identical tube-shaped pours; comparing a hollow tube with a solid round column; checking whether a specified bag count is plausible; or preparing a simple material and cost allowance before requesting supplier quotes. For structural work, dimensions and reinforcement should still come from approved drawings or a qualified professional.

How to calculate

1. The calculator opens with a complete demonstration: five tubes, 1.6 ft outside diameter, 1.3 ft inside diameter, 8 ft high, 150 lb/ft³ density, 60 lb bags, and 5% waste. Results and a validated Excel workbook are available immediately.
2. Replace the demonstration dimensions and select the unit beside each field. Unit changes convert the current value, so the physical size remains unchanged.
3. Enter the concrete density and bag size from the product data. Set Waste to reflect likely spillage, irregular forms, and handling loss.
4. Choose the Result volume unit. Review Bags needed, Concrete volume, Concrete weight, Weight with waste, Total cost, the material breakdown, and the detail table.
5. Select a Cost basis and enter Price. Download Excel exports the current typed inputs and calculations. Reset clears the demonstration values, results, and workbook state; Download Excel stays disabled until a complete valid state is entered again.

Input guide

Outer diameter is a required positive decimal and must exceed Inner diameter; for example, 1.6 ft. Increasing it raises the annular cross-sectional area quickly because diameter is squared. Inner diameter is required and may be zero for a solid cylinder; 1.3 ft is the sample. Do not enter wall thickness in this field. Height is the required axial length of each tube, such as 8 ft. Quantity is a required whole number of identical pieces, such as 5; fractional tube counts are rejected.

Density is the required wet concrete density, accepted as lb/ft³ or kg/m³; the sample uses 150 lb/ft³. Use product or mix documentation rather than dry cement density. The NIST volume-unit guidance helps distinguish cubic length units used in this calculation. Bag size is the required package weight, such as 60 lb. Waste is an optional percentage from 0 to 100; the sample uses 5%. A higher value increases required weight and bags but does not change net geometric volume. Result volume unit only changes display and workbook units. Cost basis selects whether Price means dollars per bag, dollars per displayed volume unit, or dollars per tube. Price is optional and must be nonnegative; enter 6.50 for $6.50 per bag in the startup example.

Output guide

Bags needed is the primary whole-bag purchase estimate after waste. Concrete volume is the exact geometric total before waste in the selected unit. Concrete weight equals net volume times density. Weight with waste adds the chosen percentage. Total cost uses the selected Cost basis; it is an estimate and excludes tax, delivery, equipment, labor, and reinforcement. The summary pills repeat Volume, Weight, Bags, and Waste from the same model.

The Material breakdown shows Net concrete, Waste allowance, and Purchased bag capacity. Purchased capacity can exceed Weight with waste because bags are rounded up. In the detail table, Per tube divides the project model by Quantity, Project total reports the full job, and Unit identifies the active display unit. A zero waste allowance is valid; zero or negative physical dimensions are not.

Worked example

For the startup dimensions, the annular area is π/4 × (1.6² – 1.3²) = 0.6833 ft². Multiplying by 8 ft and 5 tubes gives 27.3319 ft³, or 1.0123 yd³. At 150 lb/ft³, net weight is 4,099.78 lb. Adding 5% waste gives 4,304.77 lb. Dividing by 60 lb per bag gives 71.7461, so the purchase quantity rounds up to 72 bags. At $6.50 per bag, Total cost is $468.00.