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Calculate concrete volume and bags needed for deck post footings. Get accurate estimates for cylindrical concrete footings.
Should be below frost line + 6"
Deck footings are the foundation of your deck structure, transferring the weight of the deck to the ground below. Properly sized and installed footings prevent settling, shifting, and frost heave damage.
| Diameter | Application | Load Capacity | Deck Size |
|---|---|---|---|
| 8" | Light duty / Low decks | Up to 3,000 lbs | Small (<100 sq ft) |
| 10" ★ | Standard residential | Up to 5,000 lbs | Medium (100-300 sq ft) |
| 12" | Heavy duty / Multi-level | Up to 8,000 lbs | Large (300-500 sq ft) |
| 14" | Extra heavy / Hot tubs | Up to 12,000 lbs | Large with heavy loads |
| 16" | Commercial applications | 15,000+ lbs | Commercial structures |
★ Most common size for residential deck construction
Footings must extend below the frost line to prevent frost heave. Check your local building codes for exact requirements.
| Region / Climate | Typical Frost Line | Min. Footing Depth |
|---|---|---|
| Southern US (FL, TX, AZ) | 0-6" | 12" |
| Mid-Atlantic (NC, VA, TN) | 12-18" | 24" |
| Midwest (OH, IL, IN) | 30-36" | 42" |
| Northeast (NY, PA, NJ) | 36-48" | 48-54" |
| Northern US (MN, WI, MI) | 48-60" | 54-66" |
| Alaska / Canada | 60-80" | 72-90" |
Volume = π × r² × hWhere r = radius in feet, h = height/depth in feet
Bags = Volume (cu ft) ÷ Yield per Bag80lb bag yields ~0.60 cu ft of concrete
Total Bags = Calculated Bags × 1.1010% waste factor for spillage and overfill
| Bag Size | Yield (cu ft) | Bags per Cu Yd | Best For |
|---|---|---|---|
| 40 lb | 0.30 cu ft | 90 bags | Small repairs, easier to carry |
| 50 lb | 0.375 cu ft | 72 bags | Medium projects |
| 60 lb | 0.45 cu ft | 60 bags | Good balance of weight/volume |
| 80 lb ★ | 0.60 cu ft | 45 bags | Most cost-effective for large jobs |
★ Most common choice for deck footing projects