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Pile Load Capacity Calculator

Work out pile load capacity instantly with clear inputs, formula shown and shareable results.

About Pile Load Capacity Calculator

A pile carries load two ways: friction along the shaft, the perimeter area times average unit friction, and bearing at the toe, the base area times end bearing pressure. Their sum is the ultimate capacity, and a factor of safety of 2.5 gives the safe working load. Long slender piles are friction-dominated, short piles to rock are end-bearing.

Formulas

Ultimate capacity

Qu = pi D L x fs + pi D²/4 x qb

Working load

Q safe = Qu / 2.5

Worked example

With the default values below, Pile Load Capacity Calculator returns Safe working load of 534.1. Change any input above and every figure here is recalculated in your browser.

Inputs used

Pile diameterminimum 0.05 m
0.5 m
Embedded lengthminimum 0.1 m
15 m
Average skin frictionminimum 0 kPa
40 kPa
End bearing pressureminimum 0 kPa
2,000 kPa

Results

Safe working load
534.1 kN
Ultimate capacity
1,335.2 kN
Shaft friction capacity
942.5 kN
End bearing capacity
392.7 kN

Step by step

  1. 1Values used
  2. 2Ultimate capacity
  3. 3Working load
  4. 4Safe working load= 534.1 kN
  5. 5Ultimate capacity= 1,335.2 kN
  6. 6Shaft friction capacity= 942.5 kN
  7. 7End bearing capacity= 392.7 kN

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 1 decimal place, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • Preliminary estimate only. Pile capacity must be established by a qualified geotechnical engineer from site investigation data and confirmed by pile load testing.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Preliminary estimate only. Pile capacity must be established by a qualified geotechnical engineer from site investigation data and confirmed by pile load testing.

Frequently Asked Questions

How is the Pile Load Capacity figure worked out?

Qu = pi D L x fs + pi D²/4 x qb. A pile carries load two ways: friction along the shaft, the perimeter area times average unit friction, and bearing at the toe, the base area times end bearing pressure.

Do both components reach their maximum together?

No. Shaft friction peaks at small displacement while end bearing needs much larger movement, which is why some methods apply different partial factors to each.

What values do I need to enter?

This calculator takes 4 inputs: Pile diameter, Embedded length, Average skin friction, End bearing pressure. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.

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Pile Load Capacity Calculator – Calculate Safe working load