Concrete Footing Calculator
Estimate concrete for deck piers and foundation footings
For round footings
Depth below ground
Total footings needed
Volume per Footing
—
cubic feet
Total Volume
—
cubic yards
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
Proper footings are the foundation of any solid structure. Our concrete footing calculator helps you determine exactly how much concrete you need.
- Check local building codes for frost depth requirements
- Determine footing diameter based on structure load
- Enter footing dimensions and quantity
- Add 10% extra for variations in hole size
- Consider using tube forms
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
Volume per footing = pi x (Diameter/2)^2 x Depth
Total volume = Volume per footing x Quantity
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 deep should concrete footings be?
Footings should extend below the frost line (12"-60"+ depending on state). Check local building codes.
What diameter should deck footings be?
Standard deck footings are 12"-16" in diameter for residential decks. Larger decks may need 18"-24".
How much concrete per footing?
A 12" diameter footing that is 36" deep needs about 0.24 cubic feet or roughly 1 bag of 80lb concrete.