Bearing capacity theory to apply. Terzaghi is simplest (no depth/shape factors). Meyerhof, Hansen, and Vesic add correction factors and are preferred for modern design. If omitted, defaults to Meyerhof as a widely accepted general-purpose method.

Footing geometry. Strip footings are continuous (L >> B). Rectangular requires footing_length_m to be specified. If omitted, defaults to square footing.

Footing width (B) in meters, measured along the shorter plan dimension. Typical: 0.6-3.0 m for spread footings, 3-10 m for mat foundations.

Footing length (L) in meters, measured along the longer plan dimension. Required for rectangular footings; ignored for strip, square, and circular. Only required when footing_type is 'rectangular'.

Depth of footing embedment (Df) in meters, measured from ground surface to the base of the footing. Typical: 0.5-2.0 m for shallow footings, deeper for frost or scour.

USCS soil classification (e.g. 'GP', 'CL', 'SM'). If provided, default friction angle, cohesion, and unit weight are looked up from the soil properties table. Manual values override these defaults.

Internal friction angle (phi) of the bearing soil in degrees. Typical: 28-36 for sands, 0-5 for saturated clays. If omitted, looked up from the soil properties table using soil_type. Provide either this or soil_type.

Undrained shear strength or effective cohesion (c) in kPa. Typical: 0 for clean sands, 10-200 for clays. If omitted, looked up from the soil properties table using soil_type. Provide either this or soil_type.

Total or dry unit weight of the bearing soil in kN/m3. Typical: 15-22 kN/m3 for most soils. If omitted, looked up from the soil properties table using soil_type. Provide either this or soil_type.

Depth from ground surface to the groundwater table in meters. If within the influence zone (Df + B below surface), effective unit weight is reduced for buoyancy. If omitted, no water table correction is applied.

Factor of safety applied to ultimate bearing capacity (qu) to obtain allowable capacity (qa). Typical: 2.5-3.0 for permanent structures per most building codes. If omitted, defaults to 3.0 per standard geotechnical practice.