Footing Size Calculator

Size concrete footings based on load and soil bearing.

FOOTING AREA
sq ft
required

Usage Tip

Always consult a structural engineer for load-bearing footings. Keep footings 12 in below the frost line.

THE MATH
Area = Load × Safety ÷ Soil PSF
Where: side = √Area × 12 (inches)
• Soil bearing 1000–3000 PSF typical
• Minimum 12 in deep below frost line
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The calculators and tools on Formula Factory are provided for general guidance and informational purposes only. Results are estimates based on standard formulas and the values you enter — they do not constitute professional engineering, electrical, or architectural advice. Always verify calculations with a qualified professional before making decisions for any safety-critical, code-compliance, or commercial application. Formula Factory makes no representations or warranties as to the accuracy or completeness of any result, and accepts no liability for errors, omissions, or any outcomes arising from reliance on this information.