What strip footings do
A strip footing is the wide concrete base a foundation wall sits on. It spreads the wall's load over enough soil area to prevent settling. Because footings carry the whole structure, their size is structural — when a code or engineer specifies dimensions, those numbers win over any calculator.
Typical widths and depths
A common residential strip footing is 16 inches wide by 12 inches deep, but soft soils call for wider footings and cold climates call for deeper ones: footings must sit below the local frost line or freeze-thaw will heave them. Frost depth varies hugely by region, so check your local building code before you dig — this calculator does the volume math, not the engineering.
Measuring footings
Run a tape around the full perimeter and add up every straight run — footings are usually one continuous pour. Measure width and depth in inches inside the trench or forms. A 20-foot run at 16 inches wide and 12 inches deep: 20 × (16 ÷ 12) × (12 ÷ 12) = 26.7 ft³ = 0.99 cubic yards, about 45 eighty-pound bags before waste.
Ordering for footings
Footing concrete is almost always ready-mix — even a modest foundation perimeter passes the half-yard rule quickly, and footings must be poured continuously to avoid cold joints. Add each run to the project total above if your job combines footings with a slab.