Foundations

Bearing Capacity Calculator

Screen shallow foundation bearing capacity using a Terzaghi-style calculation.

Engineering schematic

Shallow footing bearing model

Static symbolic figure. Enter project values in the calculator fields below.

Shallow footing section showing width B, embedment depth D sub f, bearing pressure q sub u, bearing zone, and soil parameters c, phi, and gamma. — Symbols
B
footing width
Dƒ
embedment depth to foundation base
qᵤ
ultimate bearing pressure
c, φ, γ
cohesion, friction angle, and soil unit weight

Result

Allowable bearing pressure: 4000.33 psf or kPa in consistent input units

30.14

18.4

N gamma

22.4

Ultimate bearing capacity

12001

Allowable bearing capacity

4000.33

Step-by-step calculation

Surcharge at footing base
$q=\gamma D_f=120\times3=360$
Bearing-capacity factors
$\phi=30^{\circ},\quad N_c=30.14,\quad N_q=18.4,\quad N_\gamma=22.4$
Capacity components
$q_c=0,\quad q_q=6624.4,\quad q_\gamma=5376.6$
Ultimate and allowable capacity
$q_u=12001,\qquad q_{\mathrm{all}}=\frac{12001}{3}=4000.33$

What this means

This is a preliminary Terzaghi-style estimate. Settlement, groundwater, load inclination, and local code checks may govern design.

Assumptions

General shear bearing model
Level ground and concentric vertical load
Consistent unit system
Groundwater corrections are not included

Formula Used

q_u=cN_c s_c+\gamma D_fN_q+\frac{1}{2}\gamma BN_\gamma s_\gamma

Step-by-Step Example

For c=0, gamma=120 pcf, B=4 ft, Df=3 ft, phi=30 deg, FS=3, allowable pressure is about 2,992 psf.

Engineering Notes

Check units, assumptions, boundary conditions, groundwater, drainage, and whether the simplified method is appropriate before using a result in any project decision.

FAQ

Does the calculator include settlement?

No. Bearing and settlement are separate checks; settlement often controls.

Can I use metric units?

Yes, if all stress and length inputs are internally consistent.

Related Engineering Guides

Terzaghi Bearing Capacity ExplainedReview the bearing-capacity terms, factors, assumptions, and limitations.Ultimate vs. Allowable Bearing CapacityDistinguish gross, net, ultimate, and allowable pressures before sizing a footing.Spread Footings: Applications and LimitationsConnect bearing resistance with settlement, eccentricity, structural checks, and construction.