This concrete footer volume calculator finds how much concrete a continuous footing or footer needs. Enter the footing length, width, and depth above to get the volume in cubic yards plus a waste allowance.
How to use this calculator
- Enter the total footing length in feet.
- Enter the trench width and depth.
- Read the required cubic yards and bags.
How is footing volume calculated?
Volume (ft³) = Length × Width × Depth (all in feet) Cubic yards = Volume (ft³) ÷ 27
Example calculation
For a 40 ft footing, 24 in wide and 12 in deep:
- Volume = 40 × 2 × 1 = 80 ft³
- Cubic yards = 80 ÷ 27 = 2.96 yd³
- Add 10% for trench slump → order about 3.3 yd³
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Frequently Asked Questions
How do I calculate concrete for a footing?
Multiply the footing length, width, and depth in feet, then divide by 27 for cubic yards. A 40 ft footing 2 ft wide and 1 ft deep needs about 3 cubic yards.
How deep should a footing be?
Footings must sit below the frost line and on undisturbed soil; depth is set by local code and load, commonly 12 inches or more.
Should I add extra concrete for footings?
Yes. Trench walls slump and widen, so add 10 percent and round up, especially in loose or wet soil.