Foundation Load Bearing Capacity Calculator
Engineering check tool: Determine if your soil can support the house load. Calculates ground pressure vs. soil resistance and outputs a Safety Factor.
About
A foundation failure is rarely due to the concrete breaking; it is almost always due to the soil shearing or settling under the weight. This calculator performs a critical geotechnical check: it compares the pressure exerted by your footing against the bearing capacity of the soil. If the pressure exceeds the soil's resistance limit, the building will sink, leading to catastrophic structural failure.
This tool calculates the Safety Factor (SF). In engineering, a generic Safety Factor of 1.0 means failure is imminent. A factor of 2.0 to 3.0 is standard for residential foundations to account for soil variations and moisture changes. Use this to size your footings correctly before pouring concrete.
Formulas
The calculator determines the stress (σ) applied to the ground and compares it to the soil's Ultimate Bearing Capacity (qu).
Where P is the Total Load (Dead + Live) and A is the Footing Area. If SF < 2.0, the design is considered unsafe for long-term settlement.
Reference Data
| Soil Type | Bearing Capacity (kg/cm²) | Bearing Capacity (kPa) | Drainage Quality |
|---|---|---|---|
| Bedrock (Sound) | 40+ | 4000+ | Excellent |
| Dense Gravel / Sand Mix | 4.0 - 5.0 | 400 - 500 | Very Good |
| Coarse Sand (Compact) | 3.0 - 4.0 | 300 - 400 | Good |
| Fine Sand (Compact) | 2.0 - 3.0 | 200 - 300 | Fair |
| Sandy Loam / Firm Clay | 1.5 - 2.0 | 150 - 200 | Medium |
| Soft Clay / Silt | 0.5 - 1.0 | 50 - 100 | Poor (Risk) |
| Peat / Organic Soil | NULL | NULL | Unsuitable |