Concrete Post
Figure concrete and bags for setting fence posts.
About Concrete Post
Each cylindrical post hole is treated as a cylinder, summed over all posts, and converted into ready-mix bags. Post holes need concrete below the frost line to stay plumb, and bag logging keeps the finishing count accurate.
Formula
Concrete Post
Hole = pi x (diameter/2)^2 x depth; each bag yields 0.6 cu ft
- 80-lb bag
- Fast-set concrete bag making about 0.6 cu ft
Worked example
With the default values below, Concrete Post returns Concrete Volume of 8.18. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Number of postsminimum 1
- 6
- Hole depthminimum 0.5 ft
- 2.5 ft
- Hole diameterminimum 4 in
- 10 in
- Price per bagminimum 0
- 6
Results
- Concrete Volume
- 8.18 cu ft
- Volume
- 0.30 cu yd
- 80-lb Bags
- 14
- Total Cost
- $84.00
Step by step
- 1Values used
- 2Concrete Post
- 3Concrete Volume= 8.18 cu ft
- 4Volume= 0.30 cu yd
- 580-lb Bags= 14
- 6Total Cost= 84.00
Assumptions and limits
- The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Concrete Post calculated?
Hole = pi x (diameter/2)^2 x depth; each bag yields 0.6 cu ft Each cylindrical post hole is treated as a cylinder, summed over all posts, and converted into ready-mix bags.
Why does Concrete Post matter?
Post holes need concrete below the frost line to stay plumb, and bag logging keeps the finishing count accurate.
What values do I need to enter?
This calculator takes 4 inputs: Number of posts, Hole depth, Hole diameter, Price per bag. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.