Concrete Footing Calculator
Calculate the exact yardage needed for continuous strip foundations and circular pier footings.
Footing Dimensions
Concrete Required
Bags Needed
For estimation purposes only. Verify structural calculations with a licensed engineer.
Concrete Foundation Calculator
The structural integrity of any building begins underground. If you run short of concrete while pouring a continuous trench foundation, you risk creating a "cold joint"—a seam between cured and fresh concrete that becomes a severe structural weak point.
Using a highly accurate concrete footing calculator ensures you order exactly the right amount of ready-mix concrete to pour your foundation in a single, monolithic pass. Whether you are building a small retaining wall or an entire residential home, our foundation calculator will quickly generate your materials list.
How to Calculate Concrete for Footings
There are two primary types of foundation footings: Continuous Footings (long trenches) and Pier Footings (vertical cylinders).
1. Continuous Footing Calculator (Strip Foundation)
A continuous footing is a trench dug into the earth that will eventually support a block wall or poured concrete wall. To use a continuous footing calculator, you first need to find the total linear feet of the trench. If you are building a 20ft by 20ft square garage, the total linear length is 80 feet.
Length (ft) × Width (ft) × Depth (ft) = Total Cubic Feet
Total Cubic Feet ÷ 27 = Cubic Yards
2. Concrete Pier Footing Calculator (Sonotubes)
Pier footings are used for decks, porches, and pole barns. Because they are dug with an auger, they are perfectly cylindrical. To use a concrete pier footing calculator, you must calculate the volume of a cylinder.
Radius = Diameter ÷ 2
Volume = π × r² × Depth
Our footing volume calculator handles both of these complex shapes automatically. Simply select your footing type at the top of the tool.
Why Trench Walls Require Extra Waste Factor
When pouring a perfectly formed above-ground slab, a 5% waste factor is usually sufficient. However, when pouring a below-ground foundation footing directly into a dirt trench, you must order at least 10% to 15% extra concrete.
Why? Because backhoe buckets and hand-shovels cannot dig a perfectly square, plumb trench. The dirt walls will inevitably slough off, widening the trench and requiring significantly more concrete to fill the voids. Always pad your foundation calculator estimate accordingly.