Footings are the part of the job nobody sees and the inspector cares about most. The calculator above prices them by the linear foot, at an example rate of $28, which is how most footing work gets bid: measure the run, apply the rate, and keep the spec inside the rate.
Why footings price by the foot
Everything about a footing scales with length. The trench, the forms, the rebar, and the concrete all grow foot by foot along the run. What does not belong in the unit is depth and width; those belong in the rate. A footing dug twice as deep is not twice the linear feet, it is a more expensive foot. If you pour footings at more than one common spec, carry a rate for each rather than adjusting one number in your head at the truck window.
The math is quick. A 24 by 24 detached garage has a 96 foot perimeter. At the example $28 rate, the footing run is 96 x $28, which is $2,688, before the slab inside it. For that half of the job, see the concrete slab cost calculator and the worked numbers on the 24x24 slab cost page.
Depth is your local code’s call
Footings have to reach below the frost line, and frost depth changes dramatically by region. A footing that passes in one state would be laughed out of an inspection two states north. Do not quote from a rule of thumb: your local code sets the depth, and the soil on site gets a vote too. Soft or disturbed ground can mean digging past the code minimum to reach bearing, so leave yourself language in the quote for conditions below grade that nobody can see from the driveway.
Schedule around the inspection
A footing pour has a gate in front of it: the trench and steel get inspected before concrete goes in. That shapes the whole week. An open trench is exposure, and rain between digging and inspection can mean pumping water or re-digging collapsed sections at your expense. Book the inspection when you book the mud, keep the window between dig and pour short, and price the risk on jobs where you cannot.
Footings usually lead the rest of the pour, so quote both at once. How to price a concrete slab covers the flat side. PriceDesk puts the whole rate sheet on your phone with your numbers, free for 14 days.