Terzaghi Bearing Capacity

Terzaghi (1943) Bearing Capacity Calculator

Ultimate bearing capacity for strip, square, and circular footings using Terzaghi's general shear failure equation, q_u = cN_cS_c + qN_q + ½γBN_γS_γ (Terzaghi 1943; Das & Sivakugan 2019 9th SI, §6.3 Eq. 6.2).

Groundwater note: The current build assumes the water table is well below the failure zone (no GWT correction). When the water table is within or above the influence zone, apply Das & Sivakugan (2019) §6.5 — Modification of Bearing Capacity Equations for Water Table, using one of the three cases (Case I: GWT in q-term zone above footing; Case II: GWT between footing base and depth B below; Case III: GWT below B). Substitute the appropriate effective unit weight (γ^' = γ_sat − γ_w) into the γ or q term as required.

Soil Parameters

Cohesion, c' (kPa)

Moist Unit Weight, γ (kN/m³)

Saturated Unit Weight, γ_sat (kN/m³)

Water Table Depth, D_w (m) — leave blank or -1 for no GWT

Angle of Internal Friction, φ' (deg)

Foundation Parameters

Foundation Type

Width of Foundation, B (m)

Depth of Foundation, D_f (m)

Factor of Safety, FS

References & Methodology

Das, B.M. & Sivakugan, N. (2019). Principles of Foundation Engineering, 9th Edition, SI. Cengage Learning. Ch. 6 — Shallow Foundations: Ultimate Bearing Capacity: §6.3 Terzaghi's bearing capacity theory; §6.4 Factor of safety; §6.5 Modification of bearing capacity equations for water table (Cases I–III); §6.6 General bearing capacity equation; §6.10–6.13 Eccentrically loaded foundations.
Terzaghi, K. (1943). Theoretical Soil Mechanics. John Wiley & Sons, New York.
Terzaghi, K. & Peck, R.B. (1967). Soil Mechanics in Engineering Practice (2nd ed.). Wiley.
Vesic, A.S. (1973). Analysis of ultimate loads of shallow foundations. J. Soil Mech. and Found. Div., ASCE, 99(SM1), 45–73.
NAVFAC (1986). Design Manual 7.02 — Foundations and Earth Structures, Ch. 4 — Bearing capacity and groundwater corrections.