Get the volume of a square footing.
⚙️Calculation Parameters
📊Calculated Output
How Square Footing Volume Calculator Works?
To size a square footing, the Square Footing Volume Calculator multiplies length, width and thickness. The process takes 4 steps.
Enter length and width
Type both sides. A square pad has equal sides, such as 24 in × 24 in (61 cm × 61 cm).
Enter the thickness
Type the depth of the pad, such as 8 in or 12 in.
Multiply
The calculator multiplies the 3 dimensions and converts cubic inches (in³) to cubic feet (ft³).
Read quantities
The tool reports ft³, cubic yards (yd³), cubic meters (m³), bags and bearing area.
Square Footing Volume Calculator Formula
The Square Footing Volume Calculator uses the rectangular prism formula.
Footing volume
V (ft³) = L × W × t ÷ 1,728L, W and t in inches; 1,728 in³ = 1 ft³.
Bearing area
A (ft²) = L × W ÷ 144144 in² = 1 ft².
Square vs round
V_square ÷ V_round = 4 ÷ π ≈ 1.27Same width and thickness.
Worked example: 24 in × 24 in × 12 in pad
- V = 24 × 24 × 12 = 6,912 in³
- 6,912 ÷ 1,728 = 4.00 ft³ (0.148 yd³)
- Bags = ⌈4.00 ÷ 0.60⌉ = 7 bags of 80 lb
Square Footing Volume Calculator Conversion Table
The square footing conversion table lists 6 square pads with volume, bags and bearing area.
| Footing | ft³ | yd³ | m³ | 80 lb bags | Bearing ft² |
|---|---|---|---|---|---|
| 16 in × 16 in × 8 in | 1.19 | 0.044 | 0.034 | 2 | 1.78 |
| 20 in × 20 in × 8 in | 1.85 | 0.069 | 0.052 | 4 | 2.78 |
| 24 in × 24 in × 8 in | 2.67 | 0.099 | 0.076 | 5 | 4.00 |
| 24 in × 24 in × 12 in | 4.00 | 0.148 | 0.113 | 7 | 4.00 |
| 30 in × 30 in × 12 in | 6.25 | 0.231 | 0.177 | 11 | 6.25 |
| 36 in × 36 in × 12 in | 9.00 | 0.333 | 0.255 | 15 | 9.00 |
A square pad holds 27% more concrete than a round pad of the same width.
What is Square Footing Volume Calculator?
A Square Footing Volume Calculator is a concrete calculator for square and rectangular footing pads poured under piers, posts and columns.
Square pads are easy to form with 4 boards and easy to dig with a shovel. Many deck and porch plans call for a 24 in × 24 in × 12 in pad, which takes 4 ft³ of concrete, or 7 bags of 80 lb mix. The calculator handles rectangles as well, for pads under 2 posts or walls.
Square pads give 27% more bearing area than round pads of the same width.
What are the uses of Square Footing Volume Calculator?
There are 4 main uses of the Square Footing Volume Calculator.
Deck pads
Builders pour square pads under precast or tube piers.
Formed footings
Crews build 4-board forms and pour to the top.
Rectangular pads
Contractors size pads under double posts.
Load checks
Designers compare pad area with required bearing.
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