Concrete footing calculator
Estimate concrete for a continuous footing.
Enter the run, width and depth of your footing to get the concrete volume, a recommended order size, and bag counts if you're mixing by hand.
Enter your footing
Standard footing width/depth is 12″ × 12″ for a typical residential wall or fence footing — check your local code before pouring.
Results
- Volume needed
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- Recommended order
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- Estimated cost
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Bagged mix alternative
- 40 lb bags—
- 60 lb bags—
- 80 lb bags—
Bag counts include your waste % and round up to whole bags.
Estimates only — footing size and depth are structural decisions. Confirm with your local code or an engineer before pouring.
How it's calculated
A trench, not a slab.
A footing is a continuous strip of concrete rather than a flat area, so its volume comes from linear run × width × depth (both converted to feet), instead of the length × width × thickness formula used for slabs. We add your waste percentage and round bag counts up to whole bags, since footings are usually the first pour on a project — a fence line, a wall, or a deck's perimeter support.
FAQ
Common questions
How wide and deep should a footing be?
12 inches wide by 12 inches deep is a common baseline for a residential wall or fence footing on stable soil, but requirements vary by structure, soil type and local frost depth. Always confirm the size with your local building code or an engineer before pouring.
Does a footing need to go below the frost line?
In climates that freeze, yes — footings are typically poured below the frost line so seasonal ground movement doesn't heave and crack them. Check your local building department for the frost depth in your area.
Do footings need rebar?
Most structural footings use rebar for tensile strength, especially under load-bearing walls or deck posts. Fence-post footings are sometimes poured plain. Follow your local code or an engineer's spec for your specific project.
How is footing volume different from a slab?
A slab's volume comes from area × thickness. A footing is a continuous trench, so its volume comes from its linear run × width × depth — that's what the calculator above computes.
Building something else?