Bearing Capacity

Shallow foundation ultimate & allowable bearing — Vesic general equation with shape/depth factors.

Soil strength values (c, φ, γ, lateral-bearing) must come from a project-specific geotechnical report — the pre-filled defaults are illustrative placeholders, not safe assumptions.

Design diagram — updates live with your inputs

Footing Geometry

Footing width B (ft)

Footing length L (ft) = B for square

Footing depth Df (ft) To base of footing

Soil Properties

Soil cohesion c (psf) 0 for sand

Friction angle phi (deg)

Soil unit weight (pcf)

Water table depth (ft) Below grade; large = none

Design

Factor of safety On ultimate bearing

Applied pressure (psf) Optional — checks against q_allow

IBC 2021

Validation, assumptions & limitations Download validation report (PDF) ↗

This calculator is verified by 4 independent tests comparing its output against closed-form statics, NDS/SDPWS design-standard values and published worked examples. Full case-by-case results are in the PDF report.

Assumptions

Level ground, concentric vertical load, drained strength parameters.
Vesic bearing factors with shape (Vesic) and depth (Hansen) factors.
Water table adjusts the surcharge and base unit weight (buoyant).

Limitations

Soil c, phi and gamma are geotechnical INPUTS — confirm with the soils report. No load inclination, eccentricity or sloping ground.
Settlement is not checked; allowable bearing may be settlement-governed.
Single homogeneous layer within the influence zone.

Results are for preliminary design and must be confirmed by a licensed engineer against the current adopted code and project-specific conditions.