Structural

How to Calculate Footing Size from Load and Soil Bearing Capacity

A preliminary footing area can be estimated from service load divided by allowable soil bearing capacity. This is only one step in foundation design.

Published August 14, 2026 · CivilToolsIndia Editorial Team

Basic formula

Preliminary footing area = Service load ÷ allowable soil bearing capacity.

Worked example

A 600 kN service load with 200 kN/m² allowable pressure gives 600 ÷ 200 = 3.0 m² preliminary area.

How to use the calculator

Enter service load and allowable SBC using the units requested. Review the area as an early sizing check.

Why design is more complex

Actual foundation design considers moments, eccentricity, settlement, punching shear, one-way shear, depth, reinforcement and soil information.

Safety note

Use project geotechnical information and qualified structural review for actual design.

Use the Footing Area Calculator

Enter your project values and get a quick preliminary calculation.

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Engineering note: Results are intended for preliminary estimation, planning and learning. Verify measurements, drawings, specifications, current rates, applicable standards and site conditions before construction or safety-critical decisions.

Frequently Asked Questions

What is the footing area formula?

Service load divided by allowable soil bearing capacity is a preliminary sizing relationship.

What is SBC?

Allowable soil bearing capacity is the permissible soil pressure used for preliminary foundation sizing.

Is this enough for footing design?

No.

Can I assume SBC?

For actual design, use a value supported by the geotechnical investigation.