Work out rigging capacity instantly with clear inputs, formula shown and shareable results.
The capacity of a multi-leg sling set is not simply the sum of the legs. The angle reduces each leg's vertical contribution by its sine, and on a four leg set only three legs are assumed to carry load because a rigid item rarely bears evenly on all four. A further factor covers unequal leg lengths and off-centre loads.
Rigging capacity
Capacity = WLL per leg x effective legs x sin(angle) x unequal loading factor
Effective legs
Four leg sets are rated on three legs unless the load is genuinely flexible
Preliminary estimate only. Sling selection and lift planning must follow the accessory manufacturer's tables and be carried out by a competent person.
Capacity = WLL per leg x effective legs x sin(angle) x unequal loading factor. The capacity of a multi-leg sling set is not simply the sum of the legs.
A four leg set on a rigid load behaves like a table on an uneven floor: two diagonal legs take almost all the load. Rating on three is the standard conservative allowance.
This calculator takes 4 inputs: Working load limit per leg, Number of legs, Sling angle from the horizontal, Allowance for unequal loading. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.