How to Calculate Footing Size
What is Footing Size?
Footing Size Calculator helps contractors and tradespeople accurately size, spec, and estimate materials and systems.
Formula
Footing Area = Total Load / Soil Bearing Capacity
Step-by-Step Guide
- 1Calculate total load on footing, divide by allowable soil bearing
- 2Apply the formula using your project measurements
- 3Add required safety factors or waste allowances per code
Worked Examples
Input
15,000 lb load, 2000 psf soil bearing
Result
Area = 15000/2000 = 7.5 sf → use 3 ft × 3 ft footing
Common Mistakes to Avoid
- ✕Not applying code-required safety factors or derating
- ✕Forgetting to account for waste and cut losses in material estimates
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