Free Foundation Footing Calculator
Determine the minimum footing size needed to support a column or wall load based on soil bearing capacity.
lbs
psf
Minimum Footing Area
10.0 sq ft
Square Footing Side3.16 ft
Round Footing Diameter3.57 ft
Minimum Footing Area vs Total Load on Footing
Footing Sizing
Footing Area = Total Load / Soil Bearing Capacity
The bearing capacity depends on soil type: soft clay 1,000 psf, medium clay/loose sand 2,000 psf, dense sand/gravel 3,000-4,000 psf, bedrock 8,000+ psf. Always get a soil test for structural footings.
Example Calculation
20,000 lb column load on soil with 2,000 psf bearing.
- 01Area = 20,000 / 2,000 = 10 sq ft
- 02Square footing = sqrt(10) = 3.16 ft per side
- 03Use a 3.5 x 3.5 ft footing (12.25 sq ft) for safety.
Frequently Asked Questions
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