Footing Calculator
Size an isolated square footing based on column load and soil bearing capacity.
Estimates only — not professional financial, medical, legal or engineering advice. Read full disclaimer.
Calculating...
Result
Fill in the form and click Calculate to see your result here.
How it's calculated
Required Area = Column Load ÷ Safe Bearing Capacity. Square Footing Side = √(Required Area). If a proposed size is given, Base Pressure = Load ÷ Provided Area, checked against the SBC.
Example
Example: Footing Calculator
Inputs
- Column Load: 500
- Safe Bearing Capacity: 150
- Footing Length: 0
- Footing Width: 0
Outputs
- Required Area: 3.33
- Square Footing Side: 1.83
This example uses typical sample values. Adjust the inputs above to see how the results change for your own numbers.
About this calculator
The Footing Calculator determines the required base area for an isolated square footing from the column's axial load and the soil's safe bearing capacity, and - if you specify a proposed footing size - checks whether that size is adequate.
Frequently Asked Questions
SBC is determined by a geotechnical soil investigation for your specific site - it should never be assumed, as it varies widely with soil type and depth.
It's the minimum footing base area needed so the pressure the footing transfers to the soil does not exceed the soil's safe bearing capacity, calculated as load divided by SBC.
Enter your proposed footing length and width, and the calculator computes the actual base pressure and compares it to the safe bearing capacity, reporting 'Safe' or 'Unsafe'.
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