Guide · Terms
A footing is the widened concrete base at the very bottom that spreads the load onto the soil. A foundation is the whole below-grade system — footings plus the walls, piers, or slab on top. The footing is one part of the foundation, not another word for it.
People use “footing” and “foundation” interchangeably, but they are not the same thing. The footing is the bottom-most element: a strip or pad of concrete, wider than what it supports, that spreads a concentrated load over enough soil area. The foundation is everything below grade working together — the footings and the walls, piers, columns, or slab that transfer the building’s weight down to them. Loads travel down the foundation and out through the footing.
| Part | What it is | Its job | Typical form |
|---|---|---|---|
| Footing | The widened concrete base at the very bottom | Spreads the load onto the soil | Wider than the wall; 12″+ wide, 6″+ thick |
| Foundation wall (stem wall) | The wall rising from the footing to the structure | Carries the building down to the footing | Concrete or block, 8–10″ typical |
| Foundation (whole system) | Footings + walls/piers/slab together | Transfers the entire building load to the ground | The complete below-grade assembly |
A foundation wall might carry a load of a few thousand pounds per linear foot. Set that thin wall straight on the dirt and the soil under its narrow edge would be overstressed and settle unevenly. The footing solves it by spreading the same load over a wider strip: more bearing area, less pressure per square foot. That is why footings are wider than the walls above them, and why weaker soils demand wider footings — see how wide a footing should be.
A monolithic slab pours the footing and the floor slab in one piece, with a thickened, reinforced edge doing the footing’s job. It is common in warm climates without deep frost. A stem-wall foundation, by contrast, is a separate footing with a wall built on top — the more common approach where footings must reach below a deep frost line. Either way, the load still ends up spread onto the soil by a footing, separate or built-in.
Working out a footing on a foundation? Get its concrete volume and bags on the concrete footing calculator, its dimensions on the footing size chart, and its depth on how deep footings need to be. New terms along the way are defined in the concrete footing glossary.
FootingTakeoff reads a footing plan and returns total linear feet, pad count, and an invoice at your rates — automatically.
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