Soil Bearing Capacity (Terzaghi)

How much can the ground hold up? Terzaghi's classic equation estimates the bearing capacity of a shallow footing from the soil's strength and the footing geometry.

Soil Bearing Capacity (Terzaghi)Live

foundation design

Allowable bearing pressure

400kPa

Allowable load ≈ 801 kN per metre of footing

Controls

Presets

Cohesion c (kPa)

Friction angle φ (°)

Unit weight γ (kN/m³)

Footing width B (m)

Embedment depth (m)

Factor of safety

Terzaghi's equation predicts the ultimate bearing capacity of a shallow footing as the sum of cohesion, surcharge, and self-weight terms, each with a bearing-capacity factor that grows sharply with the soil friction angle. Dividing by a factor of safety gives the allowable pressure. Educational tool, not a geotechnical design.

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Data Inspector

Nc30.1

Nq18.4

Nγ22.4

Ultimate qult1201 kPa

Governing equation

q_{u} = c N_{c} + γ D_{f} N_{q} + \frac{1}{2} γ B N_{γ} = 10 (30.1) + 27 (18.4) + \frac{1}{2} (18) (2) (22.4) = 1201 kPa

Reading this result: Mixed c-φ soil: all three terms contribute — deeper embedment and a wider footing both push the ultimate capacity higher.

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How it works

Terzaghi's bearing-capacity equation sums three contributions — cohesion, surcharge from embedment, and soil self-weight — each multiplied by a bearing-capacity factor that rises steeply with the friction angle. Dividing the ultimate capacity by a factor of safety gives the allowable pressure for foundation design. Educational tool, not a geotechnical design.

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Frequently asked questions

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The solver uses established numerical methods, but results are for research and educational purposes and should be validated against experiment or professional review before you rely on them.