Pile Capacity Calculator: Bearing and Skin Friction
Calculate ultimate and allowable pile capacity for driven and bored piles. Determine shaft friction and end bearing contributions.
Last updated: January 2026
Ultimate Capacity
3330
kN
Allowable Capacity
1332
kN
Notes:
- Verify with site-specific geotechnical report
- Consider pile group effects
- Negative skin friction may apply
- Pile load testing recommended
IMPORTANT DISCLAIMER
This calculator provides PRELIMINARY ESTIMATES ONLY and is intended for planning and budgeting purposes. Results should NOT be used for final structural design or construction without verification by a licensed Professional Engineer (PE) or Chartered Engineer (CEng).
By using this tool, you acknowledge that:
1. All calculations are indicative and may not account for site-specific conditions, load combinations, or local code requirements.
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About This Calculator
The Pile Capacity Calculator helps geotechnical engineers and foundation designers determine safe working loads for driven and bored piles in UAE and Gulf soil conditions. Calculate ultimate pile capacity from shaft friction and end bearing contributions, with appropriate factors of safety for different pile types and installation methods.
Formula
Base area = π × (D ÷ 2)²; shaft area = π × D × L
Clay: end bearing Qb = 9 × cu × base area × end factor; skin friction Qs = α × cu × shaft area × skin factor, α = min(1, 0.5 ÷ √(cu ÷ 100))
Sand and gravel: Qb = Nq × γ × L × base area × end factor, Nq = min(2 × N, 60); Qs = β × (γ × L ÷ 2) × shaft area × skin factor, β = 0.25 + 0.01 × φ
If the water table is above the pile toe, Qs is reduced by 10% × (submerged length ÷ L)
Ultimate capacity Qu = Qb + Qs; allowable = Qu ÷ factor of safety
Utilisation = applied load ÷ allowable capacity × 100
Worked example
Inputs
- Pile type: bored (cased), diameter 600 mm, length 15 m
- Soil: medium dense sand (built-in values N = 25, γ = 18 kN/m³, φ = 32°)
- Water table 5 m below the pile head
- Applied load 1,500 kN, factor of safety 2.5
Steps
- Base area = π × 0.3² = 0.283 m²; shaft area = π × 0.6 × 15 = 28.27 m²; concrete volume = 0.283 × 15 = 4.24 m³.
- Nq = min(2 × 25, 60) = 50. Bored piles use an end factor of 0.5, so Qb = 50 × 18 × 15 × 0.283 × 0.5 = 1,909 kN.
- β = 0.25 + 0.01 × 32 = 0.57 and the mid-length effective stress is 18 × 7.5 = 135 kPa, so with a skin factor of 0.7 the dry-soil skin friction is 0.57 × 135 × 28.27 × 0.7 = 1,523 kN.
- The water table is 10 m above the toe, so Qs is reduced by 10% × 10 ÷ 15 = 6.7%, giving Qs = 1,421 kN.
- Ultimate capacity = 1,909 + 1,421 = 3,330 kN; allowable = 3,330 ÷ 2.5 = 1,332 kN.
- Utilisation = 1,500 ÷ 1,332 = 113%.
Result: Allowable capacity 1,332 kN against a 1,500 kN load: 113% utilised, so the pile is flagged as insufficient.
Assumptions and limits
- The soil is a single uniform layer taken from a built-in list; the soil strengths (N, cu, γ, φ) are fixed values for each soil type, not site data. A real design uses the layered ground profile from the geotechnical report.
- The pile-type end and skin factors (driven 1.0 and 1.0, CFA 0.6 and 0.8, bored 0.5 and 0.7) are simple relative factors.
- Settlement is not estimated. It needs a recognised method or a pile load test.
- Pile group effects, negative skin friction, lateral and uplift loads, structural capacity of the pile section and the chosen installation method are not checked.
- The result is a screening estimate to compare options early, not a pile design and not a substitute for a pile load test or a geotechnical engineer's advice.
When to Use This Calculator
- Designing deep foundations for high-rise buildings
- Verifying pile capacity from load test results
- Comparing driven vs bored pile options
- Estimating pile lengths for tender submissions
- Assessing pile capacity in layered soil profiles
How to Use This Calculator
Select Pile Type
Choose driven (precast, steel) or bored (cast-in-place, CFA) pile type.
Enter Pile Geometry
Input pile diameter and length (or tip elevation).
Define Soil Layers
Enter soil stratigraphy with SPT N-values or shear strength parameters.
Set Design Parameters
Specify adhesion factors, bearing capacity factors, and FOS.
Calculate Capacity
Get shaft friction, end bearing, and total allowable pile load.
Typical Scenarios in UAE & Gulf Projects
Geotechnical consultant designs 1.2m diameter bored piles for 50-story tower. Calculator determines 45m pile length required to reach rock and achieve 12,000 kN working load, with 65% shaft friction and 35% end bearing contribution.
Foundation engineer evaluates 600mm precast driven piles for highway bridge. Tool calculates capacity in dense sand with high N-values, recommending 25m length for 3,500 kN allowable load with FOS 2.5.
Frequently Asked Questions
What factor of safety is required for piles in the UAE?
The factor of safety on pile capacity and the load testing required are set by the design code, the geotechnical report and the authority concerned. Take them from your project requirements; higher factors can apply to tension piles.
How do I choose between driven and bored piles?
Driven piles suit: Sand/gravel soils, marine works, sites without vibration restrictions. Bored piles suit: Clay soils, urban sites, large diameters (>800mm), deep rock sockets. In UAE, CFA and rotary bored piles dominate due to dense sand profiles.
What are typical pile capacities in Dubai soil conditions?
Pile capacity depends on the ground profile, the pile type, diameter and length, and must come from the geotechnical report and the pile design. The calculator gives a screening estimate from the parameters you enter; confirm it with the geotechnical engineer and pile load tests.
Last Updated: January 2026
Standards Reference: BS EN 1997-1 Eurocode 7, ASCE Standard Pile Foundation Design, API RP 2A for Offshore
