Concrete Column Calculator
Estimate concrete for round or square columns
Round or square
Diameter for round, side for square
Height of the column
Total columns needed
Extra concrete for spillage & form variations
Volume per Column
—
cu ft
Total Volume
—
cu yd
80 lb Bags
—
bags
Estimated Cost
—
USD
Disclaimer: Results are estimates based on standard formulas. Not a substitute for professional advice from a licensed contractor, engineer, or architect. Verify all calculations before making purchasing or construction decisions.
How to Use This Calculator
Whether you are building porch columns, support pillars, or decorative posts, our calculator helps you estimate the exact amount of concrete needed.
- Determine column shape (round or square)
- Measure diameter or side length
- Enter column height and quantity
- Add 5% extra for spillage
Expert Insights
Smart analysis for your Concrete & Masonry project
Slab Thickness Guide
4" for patios, 5-6" for driveways, 6-8" for heavy vehicle loads. Our calculator references your dimensions against ACI 301-20 standards for optimal thickness recommendations.
Bag vs Ready-Mix Analysis
For pours under 1 cubic yard, 80lb bags cost less. Over 3 yards, ready-mix saves 30-50%. Our calculator factors your volume against regional pricing.
Curing & Strength Timeline
Concrete reaches 50% strength in 3 days, 70% in 7 days, and full cure in 28 days. Cold weather? Our calculator flags when heated enclosures are needed.
Calculation Formula
Round: V = pi x (D/2)^2 x H
Square: V = S^2 x H
Total = V x Qty / 27
Concrete Bag Size Comparison
| Bag Size | Bags per Cu Yd | Coverage at 4" | Best For |
|---|---|---|---|
| 40 lb | ~90 bags | ~0.30 sq ft/bag | Small repairs, fence posts |
| 50 lb | ~72 bags | ~0.37 sq ft/bag | Steps, small pads |
| 60 lb | ~60 bags | ~0.45 sq ft/bag | Patios, walkways |
| 80 lb | ~45 bags | ~0.60 sq ft/bag | Driveways, large slabs |
| Ready-Mix | 1 truck load | ~81 sq ft/yard | Projects over 1 cu yd |
Authority References
Our calculations are based on guidelines and standards from these authoritative sources:
- American Concrete Institute (ACI) — ACI 301-20 — Specifications for Structural Concrete. Learn more
- Portland Cement Association (PCA) — Concrete Slab Thickness Guidelines. Learn more
- Quikrete — Concrete Calculator & Mix Guidelines. Learn more
- NRMCA — Concrete in Practice (CIP) Series. Learn more
Frequently Asked Questions
How much concrete for a 12" round column?
A 12" diameter column, 8 ft tall, needs about 6.28 cu ft or 0.23 cu yd of concrete, about 11 bags of 80lb concrete (80 lb bag yields ~0.6 cu ft).
What size concrete column do I need?
For residential porches, 10-12" round columns are typical. Consult a structural engineer for load-bearing columns.