Metric Republic / Civil & structural engineering / Footing Size from Allowable Bearing Pressure

Footing Size from Allowable Bearing Pressure

Estimate required rectangular footing dimensions from service load, allowable bearing pressure and L/B ratio.

Updated September 2026

How it works

Estimate required rectangular footing dimensions from service load, allowable bearing pressure and L/B ratio.

Formula:
Areq = N·(1+self allowance)/qallow; B = √(Areq/(L/B)); L = (L/B)·B.

Before you use the result: Bearing pressure alone does not size a footing; settlement, stability and structural checks remain required.

Practical use

Use verified material data and project geometry. Treat results as planning estimates and compare them with the energy/thermal requirements that apply to the project.

Keep units consistent with the source information.
Use project-specific densities, pack sizes and coverage rates where provided.
Round purchasing quantities to supplier packaging and delivery rules.

How to use this calculator: Footing Size from Allowable Bearing Pressure

Estimate required rectangular footing dimensions from service load, allowable bearing pressure and L/B ratio.

Quick workflow

Enter the project values from the latest drawing, specification or verified site measurement.
Check units, material properties, allowances and any code- or supplier-specific parameters before calculating.
Review the result together with the formula, assumptions and the related checks shown on this page.

Worked example

Example inputs: Service vertical load [kN]: 800; Allowable bearing pressure [kPa]: 200; Length / width ratio L/B: 1.2; Foundation/self-weight allowance [%]: 10.

Using the sample values built into the calculator, the calculation gives approximately: Required footing area: 4.4 m²; Footing width: 1.915 m; Footing length: 2.298 m.

What the result means

Calculation method: Areq = N·(1+self allowance)/qallow; B = √(Areq/(L/B)); L = (L/B)·B.

Before using the result: Bearing pressure alone does not size a footing; settlement, stability and structural checks remain required.

Common questions

What does this calculator do?

Estimate required rectangular footing dimensions from service load, allowable bearing pressure and L/B ratio.

Which inputs should I verify?

Key inputs to verify include: Service vertical load [kN], Allowable bearing pressure [kPa], Length / width ratio L/B, Foundation/self-weight allowance [%].

Can I use this result for final design or ordering?

Use the result as a transparent planning or checking aid. Final design, code compliance, supplier selection and project-specific decisions still need to be verified where applicable. Bearing pressure alone does not size a footing; settlement, stability and structural checks remain required.

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