Concrete Footing Calculator — Yards & Bags

How the concrete footing calculator works

Round footing volume = π × radius² × depth. Rectangular = L × W × D. All dimensions converted to feet, then multiplied by the number of footings.

Formula: ft³ = π × (D/24)² × depth/12 (round)

A 12 in diameter tube × 36 in deep uses about 2.36 ft³ (0.087 yd³), or roughly 4 bags of 80 lb pre-mix.

Below the frost line — typically 24–48 in depending on your climate zone. Check your local code.

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