Sonotube & Concrete Pier Calculator
Calculate concrete volume, bag count, rebar, and J-bolt requirements for sonotube pier foundations. Supports common pier diameters from 8 to 16 inches with accurate volume calculations using the cylinder formula.
Concrete Pier Estimate
Concrete Volume
Volume per Pier
3.14 cu ft
12" x 4.0 ft deep
Total Volume
18.85 cu ft
0.70 cu yd
Total Weight
2,827 lbs
~150 lbs/cu ft
Bags of Concrete
80 lb Bags
32
0.6 cu ft per bag
60 lb Bags
42
0.45 cu ft per bag
Sonotubes
6
12" diameter
Hardware
Rebar Pieces
12
2 per pier, 3.5 ft each
Rebar Total Linear Ft
42.0 ft
3 x 20 ft sticks
J-Bolts
6
1 per pier
How to Use This Calculator
Select your sonotube diameter, enter the pier depth in feet and inches, and set the number of piers. Toggle rebar and J-bolt options as needed. The calculator uses the cylinder volume formula (pi x radius squared x height) to determine concrete needs per pier and total, then converts to 80 lb and 60 lb bag counts. Rebar estimates assume vertical bars extending the full depth with 3 inches of clearance at top and bottom.
Formula Used
Volume per Pier = pi x (Diameter/2)^2 x Depth. Total Volume = Volume per Pier x Number of Piers. 80 lb Bags = Total Cu Ft / 0.6. 60 lb Bags = Total Cu Ft / 0.45. Rebar Length = Pier Depth - 6 inches clearance.
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Disclaimer
This calculator is for estimation purposes only. Results may vary based on local conditions, materials, and building codes. Always consult a licensed professional before making decisions based on these calculations. MyContractorTools is not responsible for any errors or omissions.