FootingCalc

Reference · Updated July 2026

Footing Size Chart

Typical residential footing dimensions seen in practice, plus the code principles that govern them. Your approved plans always win.

Typical wall footing sizes (practice)

ApplicationTypical widthTypical thicknessNotes
8″ foundation wall (porch, cold room)16–18″6–8″Light loads
10″ basement wall, 1–2 storey house18–20″6–8″The most common residential case
10″ wall, heavier 2–3 storey loads20–24″8–10″Or per engineer on weak soils
Garage / frost walls16–20″6–8″Below frost line

"Typical" means commonly drawn on residential plans in North America — not a design table. Size is governed by soil bearing capacity, building loads, and local code amendments.

Typical interior support pads (practice)

Pad sizeDepthConcrete per pad
38″ × 38″12″~10.0 ft³ (0.37 yd³)
42″ × 42″19″~19.4 ft³ (0.72 yd³)
46″ × 46″16″~19.6 ft³ (0.73 yd³)

Compute any pad with the pad calculator.

What the code actually requires

Why footings are wider than the wall

The footing's job is to spread the wall's line load over enough soil area that the soil doesn't compress unevenly. Wider footing = more bearing area = less pressure per square foot. That's also why weak soils demand wider footings, and why an engineer sometimes overrides the standard details on a specific lot.

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FAQ

Footing size questions, answered.

What is the standard size of a house footing?
In common residential practice, wall footings under 8-10 inch concrete basement walls run 16-24 inches wide and 6-10 inches thick, with 18-20 inches wide by 6-8 inches thick very common. The governing size always comes from your approved plans, soil bearing capacity, and local code.
What is the minimum footing thickness?
The International Residential Code sets 6 inches as the minimum footing thickness for residential footings (IRC R403.1.1). Many footings are poured thicker for heavier loads or weaker soils.
How wide does a footing need to be compared to the wall?
Under the IRC, a footing must project at least 2 inches beyond each face of the wall it supports, and the projection cannot exceed the footing thickness. That is why a 10 inch wall commonly sits on an 18-20 inch footing.
How deep do footings have to be?
Footings must bear on undisturbed soil below the local frost line (IRC R403.1.4.1), which ranges from near zero in warm climates to 4+ feet in cold regions like the northern US and Canada. Your local building department publishes the required depth.