How footing concrete is calculated
Each strip is length × width × depth. Each pad is length × width × depth × quantity. The total gets your waste allowance once.
Example: a 40 ft strip, 20 in wide and 10 in deep, is 55.6 ft³ (2.06 yd³). Four 2 × 2 × 1 ft pads add 16 ft³, for 2.65 yd³ in total before waste.
Where the sizes come from
Footing size depends on soil, loads, frost depth and local code. None of these can be worked out from the wall's height or block count. If you came from the block calculator, only the wall length is carried over.
This calculator estimates concrete quantities from dimensions you supply. It does not design footings, establish bearing capacity, determine frost depth or verify building-code compliance.