Strip Footing Calculator — ft to cu yd, bags, cost
How to use this calculator
Select the footing layout — straight run, L-shape (2 sides), U-shape (3 sides), or full rectangle perimeter. Enter each segment length in feet, inches, and fractions. Set the footing width and depth, then adjust waste allowance. Results update instantly.
Cost — pick ready-mix delivery per yd³, 80-lb bags, or 60-lb bags to get total material cost.
Reinforcement — longitudinal rebar #4 or #5 running lengthwise, plus optional stirrups/ties per ACI 318-19, with lap splices at 40db.
Labor — rate per linear foot, per yd³, or a flat price. Grand total sums all active sections.
Saved Calculations
| Time | Layout | Length | Vol yd³ | Concrete $ | Rebar | Rebar $ | Labor | Total |
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How to Calculate Concrete for a Strip Footing
This strip footing calculator estimates concrete volume in cubic yards, number of pre-mixed bags (60 lb and 80 lb), total weight, material cost, reinforcement requirements, and labor expenses for continuous footings. A strip footing (also called a continuous footing or wall footing) runs beneath load-bearing walls and distributes the structural load to the ground. Enter the footing length in feet and inches with ⅛″ precision, set the width (standard: 12″ for light loads, 16–24″ for heavy), and the depth (minimum 8″, typically below the frost line).
Formulas
Volume: V = Length × Width × Depth. For a rectangle perimeter, total length = 2 × (L + W). Volume in yd³ = V(ft³) ÷ 27. An 80-lb bag covers ≈ 0.6 ft³ (0.022 yd³); a 60-lb bag covers ≈ 0.45 ft³ (0.017 yd³). Concrete density ≈ 150 lb/ft³ (4,050 lb/yd³).
Reinforcement per ACI 318-19
Strip footings typically require longitudinal rebar (#4 or #5) running the full length, with lap splices at 40 bar diameters (40db). Standard 20-ft bars are used. Stirrups (U-shaped #3 ties) are placed at 12″–24″ on center to resist shear and hold longitudinal bars in position. Minimum concrete cover is 3″ for footings cast against soil per ACI 318-19 §20.6.1.
FAQ
How wide should a strip footing be? Typically twice the wall width. For a standard 8″ block wall, use a 16″ wide footing. For light residential, 12″ is common.
How deep should a strip footing be? Minimum 8″ depth, but must extend below the frost line (24–48″ in northern climates). The footing depth refers to the concrete thickness, not trench depth.
Do I need rebar in a strip footing? Yes. ACI 318 requires minimum reinforcement. Two #4 bars running lengthwise is the most common configuration for residential footings.
