Mechanical & Civil Engineering
Pile Group Capacity & Efficiency (Feld Rule) Calculator
Estimate pile group efficiency and total group capacity using the Feld rule for closely spaced piles.
Your inputs
Change any value to update the result instantly.
Group capacity
3,750 kN
Group efficiency (Feld)
83.3 %
Total piles
9
Sum of individual capacities
4,500 kN
What this calculator does
Pile Group Capacity & Efficiency (Feld Rule) Calculator: Applies the standard civil and geotechnical relationship for this problem so the flow, pressure, settlement or capacity can be worked out from measured site inputs.
What your result means
The headline figure is the hydraulic or geotechnical quantity implied by your site inputs. Compare it against the design criteria in the applicable code before acting on it.
Formula and working
Feld rule: reduce each pile capacity 1/16 for each adjacent pile in row/column/diagonal
- 1
Collect the inputs
Number of rows = 3; Number of columns = 3; Single pile capacity = 500 kN
- 2
Apply the formula
Feld rule: reduce each pile capacity 1/16 for each adjacent pile in row/column/diagonal
- 3
Result
Group capacity = 3,750 kN
Frequently asked questions
Symbols and assumptions
- rows
- Number of rows
- columns
- Number of columns
- singlePileCapacity
- Single pile capacity (kN)
- • Steady-state, single-phase conditions are assumed unless the page says otherwise.
- • Site inputs (soil properties, flow, roughness) come from the user's own survey or testing.
Sources and review
Reviewed 2026-09-22 · Next review 2027-09-22
- • This is an educational estimate for learning and checking, not a design deliverable.
- • Real design must follow the governing code or standard for your jurisdiction and be reviewed and signed off by a qualified engineer.
- • Safety factors, load combinations and material certification are the responsibility of the designer, not of this page.
Important limitation
This is an educational estimate based only on the values and formula shown. Verify current rates, rules, units, and professional standards before relying on the result. It is not personalized financial or investment advice.
Report a mistake or request an improvement
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