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Column & sonotube calculator

Round columns and sonotube piers — π·r²·height.

Most pours order 5–10% extra for spillage and over-excavation.

Estimated volume

0.12cubic yards· 0.089 m³· 3.14 ft³
Bag sizeYield per bagBags needed
40 lb0.3 ft³11
60 lb0.45 ft³7
80 lb0.6 ft³6
25 kg0.413 ft³8
30 kg0.496 ft³7
Planning estimate. Bag counts assume the yields above; check the yield printed on your bag, and allow extra for over-excavation and spillage. Structural and load-bearing work must follow your local building code and an engineer's specification.

Premium · cost estimator

What this pour costs

Bagged
$39.00
6 × 80 lb
Ready-mix
$33.00
0.2 yd³ ordered

Prices are yours to set and stay in this browser. Ready-mix suppliers usually have a minimum load and a short-load surcharge — check before comparing.

Premium · project

Multi-pour project & order sheet

Add this pour to a saved project to total several pours into one order, then print a clean order sheet with the bag counts and yardage to hand your supplier.

Projects are stored in this browser only — nothing is uploaded and there is no account.

Formwork

How the volume is measured

diameterheightV = π·r²·hROUND COLUMN / SONOTUBE

How this calculator works

A round column or sonotube form holds a cylinder of concrete: area π·(diameter/2)² times its height, multiplied by how many you are pouring. Enter the tube's inside diameter — that is the finished column diameter.

The volume is then converted to cubic yards (27 cubic feet to the yard) and cubic metres, and divided by each bag's yield to give a bag count — always rounded up, since you cannot buy part of a bag. Bag yields follow the published premix figures: 0.30 ft³ for a 40 lb bag, 0.45 ft³ for 60 lb and 0.60 ft³ for 80 lb, with metric bags scaled from the same mixed density.

Add a waste allowance for anything real: over-excavated trenches, uneven sub-grade, spillage and what stays in the mixer. Five to ten percent is typical; a rough excavation can need more.

Worked examples

Common column sizes, already calculated

Concrete for a 6 in sonotube, 4 ft tall0.03 yd³2 × 80 lb bagsConcrete for a 6 in sonotube, 6 ft tall0.04 yd³2 × 80 lb bagsConcrete for a 6 in sonotube, 8 ft tall0.06 yd³3 × 80 lb bagsConcrete for a 8 in sonotube, 4 ft tall0.05 yd³3 × 80 lb bagsConcrete for a 8 in sonotube, 6 ft tall0.08 yd³4 × 80 lb bagsConcrete for a 8 in sonotube, 8 ft tall0.1 yd³5 × 80 lb bagsConcrete for a 10 in sonotube, 4 ft tall0.08 yd³4 × 80 lb bagsConcrete for a 10 in sonotube, 6 ft tall0.12 yd³6 × 80 lb bagsConcrete for a 10 in sonotube, 8 ft tall0.16 yd³8 × 80 lb bagsConcrete for a 12 in sonotube, 4 ft tall0.12 yd³6 × 80 lb bagsConcrete for a 12 in sonotube, 6 ft tall0.17 yd³8 × 80 lb bagsConcrete for a 12 in sonotube, 8 ft tall0.23 yd³11 × 80 lb bags

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