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Helical Screw Anchor Pull-Out Capacity Calculator

Estimate a helical pile or anchor's ultimate capacity from its final installation torque, using the standard torque correlation method.

Computed in your browser — nothing you enter is uploaded. Figures are presented for United States against IRC 2024, and every formula is cited under regulatory standards below.

Last verified 2026-08-26 · v1.0.0

Market
Imperial · sales tax

Estimated ultimate capacity

155.69 kN

Check your inputs

Torque correlation is an empirical estimate, not a substitute for load testing on critical projects — it's most reliable when the site soil is reasonably uniform and the specific Kt factor has been validated for similar conditions.

Equivalent in lbs
35000 lb

For the dimensions entered, expect a estimated ultimate capacity of 156 kN. Moderate confidence — sound arithmetic, but allow for the variation any real site introduces. Set for United States against IRC 2024. The market selector changes both the units and the code cited.

Add the equipment this sizes

This result is a specification — 155.688 kN — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — confirmed fixes become pinned regression tests.

[Schema Verified] Computed in alignment with American Concrete Institute (ACI 318-19) formulas and International Residential Code (IRC 2024) spatial boundaries.

Regulatory standards & verification citations

  • Torque correlation method (widely used across the helical pile/anchor industry): ultimate capacity Pu = Kt x T, where Kt is an empirical torque factor specific to the shaft geometry and T is the final installation torque

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Frequently asked questions

Why does higher installation torque mean higher capacity?
As a helical anchor screws into progressively denser or stronger soil, it takes more torque to keep advancing — that increased resistance during installation correlates empirically with how much load the same soil will resist when the anchor is loaded in service.
Does the torque factor Kt ever change for the same anchor?
Kt is primarily a function of the shaft's physical geometry (diameter, round vs. square), not the soil — but always confirm the manufacturer's published Kt for your specific shaft rather than assuming a generic value.
Is torque correlation accurate enough for final design?
It's widely accepted as a reliable field verification method precisely because it reflects actual soil conditions at each specific anchor location, but engineers still typically require a minimum installation torque as a design criterion, with load testing for critical or unusual projects.