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Crane Outrigger/Mat Ground-Bearing Pressure Calculator

Check the ground bearing pressure under a mobile crane outrigger pad or cribbing mat against the site's allowable bearing capacity.

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
3.94 ft3.94 ft
Schematic, drawn to the proportions you entered — not to scale on screen.

Applied ground bearing pressure

102.19 kPa

Check your inputs

This calculator checks GROUND bearing pressure ONLY, using a reaction load YOU supply from your crane's own manufacturer-certified load chart and rigging plan — it does NOT calculate crane capacity, stability, ballast, or outrigger reaction loads, all of which must come from the crane manufacturer's certified data and a qualified rigger/operator per OSHA 29 CFR 1926 Subpart CC. Allowable ground bearing capacity must come from your own geotechnical data or a competent person's site assessment. A failing result means a larger mat, additional cribbing, or ground improvement is needed before the pick — always consult a qualified person for the final crane setup.

Outrigger reaction force
147150 N
Mat contact area
15.5 ft²
Allowable bearing capacity (user-supplied)
150 kPa

For the dimensions entered, expect a applied ground bearing pressure of 102 kPa. Of the working steps, allowable bearing capacity (user-supplied) dominates at 150 kPa. 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 — 102.188 kPa — 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

  • Applied bearing pressure = Outrigger Reaction Load × 9.81 ÷ Mat Contact Area — the standard bearing-pressure check for temporary crane pick support, using the SAME reaction load the rigger/crane operator reads directly from the crane's own manufacturer-certified load chart (this calculator does not calculate crane capacity, stability, or ballast — it only checks whether the GROUND under a known reaction load, from your own certified chart, can support it).

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

Frequently asked questions

Does this calculator determine the crane's outrigger reaction loads, capacity, or ballast?
No. It does not calculate crane capacity, stability, ballast, or outrigger reaction loads — those must come from the crane manufacturer's certified load chart and a qualified rigger/operator per OSHA 29 CFR 1926 Subpart CC. This calculator only checks whether the ground under a reaction load you already have from that certified chart can support it.
Where does the allowable ground bearing capacity value come from?
From your own geotechnical data or a competent person's site-specific assessment. Bearing capacity varies enormously with soil type, moisture content, and compaction, so there is no universal default value to assume.
What should I do if the check fails?
A failing result means a larger mat, additional cribbing, or ground improvement is needed before the pick. Always consult a qualified person for the final crane setup rather than relying on this screening check alone.