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Footing Bearing Pressure Calculator

Spread footing bearing check with eccentric loading, one-way shear, two-way punching shear, and flexural reinforcement per ACI 318 and IBC

Free footing design calculator for structural engineers and foundation designers. Check bearing pressure against soil capacity from IBC Table 1806.2, then verify one-way shear, two-way punching shear, and flexural reinforcement per ACI 318-19 Chapter 13. Handles concentric and eccentric loading with kern check , warns when partial bearing (uplift) occurs.

Pro Tip: Bearing pressure is checked at service (unfactored) loads because geotechnical capacity is already at service level. Shear and flexure are checked at factored (ultimate) loads per ACI 318. The eccentricity limit B/6 is the "kern" , if the load stays inside the middle third of the footing, the entire base is in compression.

Calculate column capacity above the footing

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Estimate soil bearing capacity from soil type

Soil Bearing Capacity Calculator →

Calculate seismic loads on the structure

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Check rebar spacing and coverage

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Footing Bearing Pressure Calculator
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How It Works

  1. Define Footing Geometry

    Choose square, rectangular, or continuous footing. Enter dimensions (L × B) and thickness h. Select column shape and dimensions for shear checks.

  2. Enter Loads

    Enter service load P (kips) for bearing check and factored load Pu (kips) for shear/flexure checks. Set eccentricity if applicable.

  3. Set Soil and Material Properties

    Select soil type from IBC Table 1806.2 for presumptive bearing, or enter a value from a geotechnical report. Set concrete f'c, steel fy, and rebar cover.

  4. Review All Checks

    The calculator runs bearing, one-way shear, two-way shear, and flexure checks. Each shows utilization ratio and PASS/FAIL. If any check fails, increase footing size or thickness.

Built For

  • Structural engineers designing isolated spread footings for building columns
  • Concrete contractors verifying footing sizes and reinforcement before pour
  • Building officials reviewing footing calculations for code compliance
  • Geotechnical engineers checking bearing pressures against recommended capacities
  • Engineering students learning ACI 318 foundation design provisions

References

  • ACI 318-19 , Building Code Requirements for Structural Concrete, Chapter 13: Foundations
  • IBC 2021 , International Building Code, Table 1806.2: Presumptive Load-Bearing Values
  • CRSI Design Handbook , Concrete Reinforcing Steel Institute (footing design examples)
  • ASCE 7-22 , Load Combinations for Foundation Design

Frequently Asked Questions

Bearing pressure is checked at service (unfactored) loads because the allowable soil bearing capacity from IBC Table 1806.2 or a geotechnical report is already a service-level value with a built-in safety factor (typically 3.0). Shear and flexure in the concrete footing are checked at factored (ultimate) loads per ACI 318 because the concrete strength-reduction factors (φ) provide the safety margin. Mixing the two would either over- or under-design the footing.
Punching shear is the tendency for the column to "punch" through the footing like a fist through paper. The critical section is a perimeter at d/2 from the column face (where d is the effective depth). The shear stress on this perimeter must not exceed the ACI 318 limit. Punching shear often controls footing thickness , if a footing fails this check, increase the thickness rather than making the footing plan larger.
When the eccentricity e exceeds B/6 (the kern), the load falls outside the middle third of the footing. This means the bearing pressure distribution goes from trapezoidal to triangular with zero pressure (uplift) on the far edge. The maximum bearing pressure increases dramatically. The calculator warns you when this happens and uses the correct triangular distribution formula. If possible, redesign to keep e within B/6.
Disclaimer: This calculator checks bearing pressure and provides simplified shear and flexure checks for isolated spread footings under concentric or uniaxial eccentric loading. Biaxial eccentricity, combined footings, strap footings, mat foundations, moment frames, and soil-structure interaction require analysis by a licensed geotechnical and structural engineer.

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