Define the screening question and evidence
This workflow is for geotechnical and civil engineering students, technicians, and engineers preparing an early screening note. The expected result is an auditable set of preliminary values and assumptions, not a statement that a site, footing, slope, or wall is safe. Identify whether the question concerns shallow-footing resistance, an infinite-slope screen, active pressure on a retaining-wall idealization, or a combination.
Before calculating, record cohesion, friction angle, unit weight, stress basis, dry or saturated condition, groundwater level, seepage direction, drainage, geometry, loads, surcharge, units, and uncertainty. Describe footing shape, B and Df, slope beta and z, or wall H. State the factor-of-safety criterion that a reviewer will apply.
Use the matching simplified path
Use bearing-capacity-calculator for Terzaghi ultimate capacity of a strip, square, or circular shallow footing. It produces q_ult and bearing factors but has no groundwater or applied-load input. Use slope-stability-calculator for the infinite-slope equation: dry means no seepage, while parallel uses saturated and water unit weights for seepage idealized parallel to the slope. Save FS, driving shear, contributions, and classification.
Use active-earth-pressure only for a smooth vertical wall with cohesionless backfill and optional uniform surcharge. Save Ka, base pressure, total force P, and resultant height. Since it has no groundwater input, hydrostatic pressure and other wall actions remain separate review items.
Check results and common failure modes
Do not call every favorable number a safety factor. q_ult is not an applied-load comparison, and wall force P is not a factor of safety. Compare slope FS with the written project criterion, then separately compare foundation pressure and wall actions with the required checks. Common failures include omitting a rising water table, using dry weight in a saturated or seepage case, applying the wall model to a rough or inclined wall, and treating an infinite-slope result as a complete landslide assessment. The calculator output is not a site investigation, geotechnical report, construction approval, or replacement for qualified engineering review.