Footing & Pier Calculators
Footings carry the load a slab only spreads. Continuous trench footings and cylindrical pier footings are priced from different shapes, so they are calculated separately here.
There are 2 calculators here: Concrete Strip Footing Calculator (concrete volume and cost for continuous strip footings) and Sonotube Deck Footing Calculator (concrete volume and cost for round tube footings).
They all work the same way: quantity first, then a waste allowance you can change, then a price built from verified figures and adjusted for your state. Cost is always a range rather than a single number, and every assumption behind it is printed on the page with its source and the date it was last checked.