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Calcimator

Pile Capacity Calculator

Estimate single pile bearing capacity including point resistance and skin friction. Uses alpha and beta methods with a factor of safety of 2.5.

Inputs

in
ft
psf
°
pcf
ft

Results

Ultimate Capacity

124,159 lb

≈ 10 elephants

Allowable Load (FS=2.5)

49,664 lb

≈ 15 small cars

Point Bearing (Qp)46,521 lb
Skin Friction (Qs)77,638 lb
How to Use This Calculator
  1. Enter pile diameter (inches), pile length (ft), soil cohesion (psf), and friction angle (°).
  2. Set soil unit weight (pcf) and groundwater depth (ft).
  3. Review ultimate pile capacity and allowable capacity with factor of safety.
  4. Verify with a site-specific geotechnical report before construction.

How the result changes with Pile Diameter

Pile DiameterUltimate CapacityAllowable Load (FS=2.5)
13142,098 lb56,839 lb
29556,555 lb222,622 lb
491,370,294 lb548,117 lb
652,273,965 lb909,586 lb

What each input means

Pile Diameter
Diameter of the pile. Common sizes: 12" precast concrete, 14" H-pile, 24-48" drilled shaft.
Pile Length
Embedded length of the pile below ground surface to the pile tip.
Soil Cohesion (c)
Undrained shear strength of the clay layers. For sand, use 0 or a small value.
Friction Angle (φ)
Internal friction angle of soil at and near the pile tip. Sand ≈ 28-38°; clay ≈ 0-15°.
Soil Unit Weight (γ)
Average total unit weight of the soil profile along the pile length.
Groundwater Depth
Depth to groundwater table below ground surface. Reduces effective stress below this depth.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Pile Diameter = 12, Pile Length = 40, Soil Cohesion (c) = 500, Friction Angle (φ) = 30 = 6 input(s) provided
  2. Calculate Ultimate Capacity
    Ultimate Capacity
    124159 = 124159
  3. Calculate Allowable Load
    Allowable Load
    49664 = 49664
  4. Calculate Point Bearing
    46521 = 46521
  5. Calculate Skin Friction
    Skin Friction
    77638 = 77638

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