Spread (Pad) Footing Calculator — ft, yd³, cost
How to use this calculator
Select a footing shape (square, rectangular, or circular), enter dimensions in feet, inches, and fractions, then set depth and number of footings. Optionally add a pedestal/column stub on top. Results update instantly with volume, weight, bags, rebar, and an interactive diagram.
Cost — choose ready-mix per yd³, 80-lb bags, or 60-lb bags.
Reinforcement — bottom mat rebar in both directions per ACI 318-19, with bar size and spacing.
Labor — rate per footing, per yd³, or flat price.
Saved Calculations
| Time | Shape | Qty | Vol yd³ | Weight | Cost |
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How to Calculate Concrete for Spread Footings
A spread (pad) footing distributes the load from a column or post over a wider area of soil. This calculator computes the concrete volume for square, rectangular, or circular footings with an optional pedestal/column stub. Enter dimensions in feet, inches, and fractions (⅛″ precision), set the footing depth (standard: 12″ for light loads, 18–24″ for heavy-duty), number of footings, and waste allowance.
Footing Volume Formulas
Square: V = side² × depth. Rectangular: V = length × width × depth. Circular: V = π × (diameter/2)² × depth. Pedestal volume is added on top. All volumes are converted to cubic yards (÷ 27) for ordering ready-mix concrete.
Reinforcement per ACI 318-19
Bottom mat rebar is placed in both directions with 3″ minimum cover. Bar sizes #3 through #6 with spacing 6″ to 18″ on center. The calculator accounts for development length and cutting waste.
FAQ
How deep should a spread footing be? Minimum 12″ for residential, 18–24″ for commercial. The depth must extend below the frost line per local codes.
What size footing do I need? Footing size depends on the column load and soil bearing capacity. A structural engineer should size footings for load-bearing applications.
