/// Short answer
concrete for a post hole — the planning answer
Post-hole concrete is estimated from the hole geometry around the post, the number of holes, and the selected product yield. The post itself displaces volume, so a solid cylinder calculation may overstate the concrete if the post diameter is not included. Enter approved hole dimensions and the exact product data; the calculator does not select depth or foundation design.
How do you estimate concrete for a post hole?
Post-hole concrete is estimated from the hole geometry around the post, the number of holes, and the selected product yield. The post itself displaces volume, so a solid cylinder calculation may overstate the concrete if the post diameter is not included. Enter approved hole dimensions and the exact product data; the calculator does not select depth or foundation design.
Concrete around a post = hole volume − post-displacement volume, multiplied by hole quantity. For circular geometry, cylinder volume uses π × radius² × depth.
/// Continue with the numbers
Run the post hole concrete calculator
Use the post-hole concrete calculator to subtract the post cylinder from each entered hole cylinder, multiply by hole count, apply waste, and optionally divide by a selected bag yield. This annular-volume estimate does not size posts or footings. Verify hole shape, bell bottoms, soil, frost, drainage, embedment, structure, and product instructions separately.
/// Keep the topic connected
Related calculators
Use the neighboring tools to keep each material, layer, and order assumption visible instead of hiding it inside one estimate.
What should you measure first?
Record the hole diameter and depth from the approved detail, then record the post diameter separately. If holes vary, group them by size rather than averaging them into one number.
- Measure hole diameter and depth, not just the post size.
- Record post diameter or section shape for displacement.
- Group corner, gate, end, and line posts if their details differ.
What should you verify before ordering?
Hole depth, diameter, frost protection, wind resistance, drainage, and setting method are project decisions. Verify them locally before using the quantity as an order number.
- Confirm the product's bag yield and mixing instructions.
- Add a separate allowance for spillage or irregular excavation only when justified.
- Check access and the number of bags that can be mixed safely.
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Related ProjectQty pages
/// Field-ready worksheet
Download the measurement checklist
Use the worksheet to record dimensions, product-label values, and verification notes locally. ProjectQty does not receive or store your project inputs.
/// Evidence trail
Sources and assumptions
This article inherits the calculator's declared source scope. Product yields, coverage, density, and label rates should be replaced with the exact product selected for the job.
Exact international-foot to meter conversion; U.S. survey-foot conversion is explicitly outside this claim.
NOAA National Geodetic Survey · Prequalified fallbackThe DSDATA Format, Appendix D: U.S. Survey Foot vs International FootIndependent confirmation that one international foot equals exactly 0.3048 meters; U.S. survey-foot conversion remains distinct.
/// Common questions
How Much Concrete Goes in a Post Hole? FAQ
Does the post volume reduce the concrete needed?
Yes, when the post remains in the hole and its shape is included. The reduction is based on post displacement, not a generic percentage.
Can I use the same hole dimensions for every post?
Only if the project detail specifies identical holes. Gate, corner, and end posts may have different requirements.
Does this calculate the correct post depth?
No. Enter the depth from a project-specific design or local requirement; the tool only calculates quantity from entered geometry.