Outrigger Pad Size Calculator

Inputs

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Size a pad from the reaction, or check the pad already on the truck.
Maximum vertical reaction at this outrigger from the crane's load chart / outrigger-reaction program for the planned pick — not the crane weight divided by four.
N
The site's allowable ground pressure (geotech report, site engineer or project criteria). This calculator does not choose it.
kPa
Shape of the pad or mat under this outrigger.
Side of the square pad, or diameter of the round pad, that you actually carry.
mm

Results

Default result
Edit inputs
Required bearing area(A_req)
1,667,000mm²
Pass

Reaction ÷ allowable ground pressure.

Also computed

Square pad side1,291mm

Round pad diameter1,457mm

Actual ground pressure(q)127.6kPa

Check mode — reaction over your pad's area.

Bearing utilizationPass0.85

Within the entered allowable.

Actual ÷ allowable; over 1.0 means a bigger pad or better ground.

Method notes 4 notes
  • Pure bearing arithmetic: area = reaction ÷ allowable pressure. The reaction comes from the crane's chart or outrigger-reaction program for the actual pick (boom over the corner, not parked), and the allowable from the site — both yours; no crane or soil tables are embedded.
  • The pad only spreads load over the area it is stiff enough to engage: a thin plate bends and bears on a smaller effective footprint. Engineered mats and cribbing carry stiffness ratings — this screen sizes the contact area, not the mat structure.
  • Track and crawler bearing, mats spanning voids/utilities, and frozen or layered ground are site-engineering questions beyond a bearing-area screen.
  • The same arithmetic for building posts is the deck footing calculator; sling-side rigging lives in the sling angle load and hitch capacity calculators.

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