Deck Footing Calculator

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Calculate the number of footings and concrete needed for your deck foundation. Enter your deck dimensions and beam spacing to determine footing locations, sizes, and concrete volume. Proper footings are critical for a safe, long-lasting deck.

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Enter Your Measurements

Results

Total Footings

9

footings

Concrete (80 lb bags)

42

bags

Total Concrete

0.92

cubic yards

Concrete per Footing

2.75

cubic feet

Beam Rows

3

rows

Footings per Row

3

footings

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Formula

Total Footings = Beam Rows × Footings per Row | Volume per Footing = π × (Diameter ÷ 24)² × (Depth ÷ 12)

How to Use This Calculator

How to Use

  1. 1

    Enter the deck length and width in feet.

  2. 2

    Enter the beam spacing (how far apart the support beams run).

  3. 3

    Enter the footing diameter in inches (12 inches is standard for most decks).

  4. 4

    Enter the footing depth in inches (must be below frost line in your area).

Frequently Asked Questions

Frequently Asked Questions

How deep should deck footings be?

Deck footings must extend below the frost line, which varies from 12 inches in southern states to 48 inches or more in northern regions. Check your local building code for the exact depth.

What size footings for a deck?

Standard deck footings use 12-inch diameter sonotubes for typical residential decks. For larger or multi-story decks, 16-inch or larger footings may be required. Your local code specifies minimum sizes based on load calculations.
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About This Calculator

This calculator uses the formula: Total Footings = Beam Rows × Footings per Row | Volume per Footing = π × (Diameter ÷ 24)² × (Depth ÷ 12). All calculations follow industry-standard methods. Results are estimates — always verify with a licensed professional for structural or code-compliant work.

Built and maintained by the CalcSmart team. Last updated March 2026.

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