Work out foundation size instantly with clear inputs, formula shown and shareable results.
A pad footing spreads the column load until the pressure on the soil is within the allowable value, so the required area is total load divided by safe bearing capacity. An allowance of about ten percent is added for the footing's own weight and the soil above it, and the side length is rounded up to a buildable 50 mm increment.
Required area
A = column load x (1 + self weight allowance) / safe bearing capacity
Square footing
Side = sqrt(A), rounded up to a practical dimension
Preliminary estimate only. Foundation design must be completed by a qualified structural engineer including settlement, thickness and reinforcement design.
A = column load x (1 + self weight allowance) / safe bearing capacity. A pad footing spreads the column load until the pressure on the soil is within the allowable value, so the required area is total load divided by safe bearing capacity.
No. This is the serviceability bearing check only. Thickness and reinforcement come from factored loads with bending, one-way shear and punching shear checks.
This calculator takes 3 inputs: Column service load, Safe bearing capacity, Allowance for footing self weight. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.