/// Short answer
concrete for footings — the planning answer
To estimate concrete for a footing, use the approved footing length, width, and depth, multiply the volume by the number of identical footings, and then apply an explicit planning allowance. For example, one 20 ft × 1.5 ft × 0.75 ft footing is 22.5 ft³, or 0.8333 yd³; with 10% waste and a 0.60 ft³ bag yield, the planning quantity is 42 bags. Footing dimensions must come from the project design.
How do you estimate concrete for footings?
To estimate concrete for a footing, use the approved footing length, width, and depth, multiply the volume by the number of identical footings, and then apply an explicit planning allowance. For example, one 20 ft × 1.5 ft × 0.75 ft footing is 22.5 ft³, or 0.8333 yd³; with 10% waste and a 0.60 ft³ bag yield, the planning quantity is 42 bags. Footing dimensions must come from the project design.
Footing volume = length × width × depth × quantity. Convert dimensions to one unit system before multiplying, then convert to cubic yards or selected bag units.
/// Continue with the numbers
Run the concrete footing calculator
Use the concrete footing calculator to multiply identical footing quantity by approved length, width, and depth, preserve the net volume, apply a visible waste allowance, and optionally divide by a selected bag yield. The 20 ft × 1.5 ft × 0.75 ft reference produces 0.8333 yd³ net and 42 bags after 10% waste at 0.60 ft³ per bag. It does not size the footing.
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Related calculators
Use the neighboring tools to keep each material, layer, and order assumption visible instead of hiding it inside one estimate.
What should you measure first?
Do not infer footing dimensions from the wall or post above it. Copy the dimensions from the approved detail or qualified review, and calculate continuous and isolated footings as separate shapes when their geometry differs.
- Separate continuous footings, pads, and pier-like shapes.
- Record quantity and spacing independently from footing dimensions.
- Confirm whether a footing has a step, key, haunch, or thickened area.
What should you verify before ordering?
A quantity calculator cannot determine bearing capacity, frost depth, reinforcement, or code compliance. Verify the design and placement sequence separately from the material takeoff.
- Confirm dimensions and quantity against the drawing.
- Use the selected mix or bag yield instead of a generic bag conversion.
- Ask the supplier whether the total volume meets its delivery minimum.
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Related ProjectQty pages
/// Field-ready worksheet
Download the measurement checklist
Use the worksheet to record dimensions, product-label values, and verification notes locally. ProjectQty does not receive or store your project inputs.
/// Evidence trail
Sources and assumptions
This article inherits the calculator's declared source scope. Product yields, coverage, density, and label rates should be replaced with the exact product selected for the job.
Exact international-foot to meter conversion; U.S. survey-foot conversion is explicitly outside this claim.
NOAA National Geodetic Survey · Prequalified fallbackThe DSDATA Format, Appendix D: U.S. Survey Foot vs International FootIndependent confirmation that one international foot equals exactly 0.3048 meters; U.S. survey-foot conversion remains distinct.
/// Common questions
How to Estimate Concrete for Footings FAQ
Can I estimate footing size from wall width?
Not safely. Wall width and footing size are different design inputs. Use the footing dimensions specified for the project.
How do I estimate several identical footings?
Calculate one footing volume and multiply by the number of identical units. Keep different sizes in separate lines.
Does the result design the footing?
No. It estimates material quantity from entered dimensions only; it does not provide structural or code approval.