Four 12-inch piers
Typical deck pier material count.
24 bagsConcrete bagsconcrete sonotube calculator
Concrete Sonotube Calculator
A Sonotube estimate is a cylinder-volume calculation: radius squared times pi times concrete height, multiplied by the number of forms.
Inputs
Results
Immediate estimateConcrete bags24 bags80 lb bags rounded up
Base volume12.57 cu ft
Waste allowance1.26 cu ft
Adjusted volume13.82 cu ft
Concrete yards0.512 cu yd
Shopping list
- 24 bags 80 lb concrete mix
Diagram
Round form pier
Each form is modeled as a solid cylinder with no post displacement.
- Tube diameter
- Concrete height
- Form count
How this calculator works
Enter tube diameter, concrete height, quantity, bag size, and waste to estimate concrete for round form piers.
Formula
The engine treats each tube as a solid cylinder and converts the total volume into bags using common bag-yield assumptions.
When this beats post-hole math
Use this standalone page when the form is poured solid or when the search intent is explicitly about tube forms rather than post displacement.
Field caution
Pier diameter, depth, reinforcement, uplift, frost depth, and inspection requirements are project-specific.
Cylinder
pi x radius squared x height x countPurchase
(volume + waste) / bag yield, rounded upAssumptions
- Shape: Solid cylindrical form with no post displacement.
- Bag yield: 80 lb bag yields about 0.6 cubic feet.
Worked examples
Tall porch pier
Shows the tall-pier caution.
49 bagsConcrete bagsFAQ
Is this the same as the post hole concrete calculator?
No. This page assumes a solid cylindrical form. The post-hole tool can subtract post displacement.
Does it include rebar?
No. Rebar is a design and code question, not a concrete-volume question.
Should I use tube height or hole depth?
Use the actual height of concrete you plan to place inside the form.
Sources and review
- Concrete Calculator, QUIKRETE. Accessed 2026-07-16.
- 2021 International Residential Code, International Code Council, 2021. Accessed 2026-07-16.
Reviewed 2026-07-16. Planning estimates only; confirm project-specific requirements.