Construction tools
Post Hole Concrete Calculator
Estimate concrete volume and whole bags from the hole geometry, post size, and bag yield you enter.
Concrete estimate
Enter the hole and post geometry, then use the yield printed on the concrete bag you plan to buy.
How this estimate works
The calculator uses concrete = (cylindrical hole volume − square post volume) × post count. A square post is subtracted from the cylindrical hole, then the final bag count rounds up using the yield you enter.
Bag yield is a product value: confirm it on the exact bag label before ordering.
Method & sources
Results are volume estimates only. The calculation assumes one cylindrical hole and one centered square post of the dimensions entered.
Important limits
- This does not recommend a hole diameter, depth, gravel base, post size, or post spacing.
- It does not assess soil, frost conditions, drainage, structural/loading needs, property boundaries, or local requirements.
- For structural or load-bearing work, use project-specific guidance and appropriate local requirements.
Reviewed references
- QUIKRETE: Concrete Calculator
Reviewed 2026-07-21. Shows post-setting bag estimates rounded up to whole bags; product yields vary by mix and bag size.
- QUIKRETE: Setting Posts in Concrete
Reviewed 2026-07-21. Distinguishes general post-setting guidance from structural or load-bearing applications; this calculator does not assess suitability.