Concrete Footing Calculator
Estimate concrete for strip or continuous footings. Enter the total footing length, width, and depth to get cubic yards, bag counts, and cost.
Results
- Concrete needed
- 1.32 cu yd
- With 10% waste
- 1.45 cu yd
- Cubic feet
- 35.56 cu ft
- Cubic meters
- 1.01 m³
- 80 lb bags
- 66 bags
- 60 lb bags
- 87 bags
- 40 lb bags
- 131 bags
Estimates only. Round up and buy a little extra to account for waste, spills, and breakage.
Sizing footings for a foundation, deck, garage, or retaining wall? This footing calculator turns total footing length, width, and depth into cubic yards and bag counts.
Footings carry the entire structure into the soil, so getting the volume — and the steel — right matters. Always confirm dimensions and depth against your local building code.
Also used as a footing concrete calculator, strip footing calculator, and continuous footing estimator.
How to use the concrete footing calculator
- Enter the total footing length in ft.
- Enter the footing width in in.
- Enter the footing depth in in.
- Enter the waste factor in %.
- Optionally add a price to estimate the total project cost.
- Read your quantities instantly — no sign-up, and you can print the estimate to take to the supplier.
Worked example
Inputs
- Total footing length
- 40 ft
- Footing width
- 16 in
- Footing depth
- 8 in
- Waste factor
- 10 %
Results
- Concrete needed
- 1.32 cu yd
- With 10% waste
- 1.45 cu yd
- Cubic feet
- 35.56 cu ft
- Cubic meters
- 1.01 m³
- 80 lb bags
- 66 bags
- 60 lb bags
- 87 bags
- 40 lb bags
- 131 bags
Using the example values above, the concrete footing calculator returns 1.32 cu yd (concrete needed). Change any field to match your own project and the numbers update instantly.
How deep do footings need to be?
Footings must extend below the local frost line and bear on undisturbed or compacted soil. In cold climates that can mean 36–48 inches deep; in warm regions 12 inches may pass. Your building department sets the minimum.
Width is typically twice the wall thickness, commonly 16–24 inches for residential walls. Add rebar continuously and keep it about 3 inches off the soil.
How much extra should I order?
Always order a little extra. A 5% waste factor suits simple, square projects; 10% is right for most jobs; bump it to 15–20% for irregular shapes, diagonal patterns, or uneven ground. Running short almost always costs more than the leftover material.
Concrete bag yields
| Bag size | Yield (cu ft) | Bags per cu yd |
|---|---|---|
| 40 lb | 0.30 | 90 |
| 50 lb | 0.375 | 72 |
| 60 lb | 0.45 | 60 |
| 80 lb | 0.60 | 45 |
Formula
Volume (cu ft) = total length × width × depth (all in feet). Cubic yards = cu ft ÷ 27. Add waste %.
Frequently asked questions
- How deep should a footing be?
- Footings must sit below the frost line and on undisturbed soil — commonly 8–12 inches deep and at least as wide as code requires for the load. Check local code.
- How wide should a footing be?
- Residential footings are typically 16–24 inches wide, usually twice the wall thickness, but always follow your local building code.
- How do I calculate concrete for a footing?
- Multiply total footing length × width × depth in feet for cubic feet, then divide by 27 for cubic yards. Convert inch measurements to feet by dividing by 12 first.
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