Sling Angle & Leg Tension Calculator
For a load hanging centrally under the hook on two, three or four legs of equal length. Measure the angle of each leg from vertical.
Tension per leg = load ÷ (legs sharing the load × cos angle from vertical). Three- and four-leg slings are calculated as if only two legs carry the load, a common conservative assumption for rigid loads. Always use the sling manufacturer’s rating tables and your lifting standard; this tool does not replace a lift plan or a competent person.
Frequently asked questions
Why does the sling angle matter?
As sling legs spread wider, each leg has to pull sideways as well as up, so the tension in each leg rises even though the load stays the same. At 60 degrees from vertical, each leg of a two-leg sling carries the full weight of the load.
Why are three- and four-leg slings calculated on two legs?
On a rigid load, small differences in leg length or attachment height mean the load is rarely shared equally, and two legs can end up carrying most of it. Assuming only two legs take the load is a common conservative approach. Follow your rigging standard and the sling manufacturer’s rating tables.
What is the maximum sling angle?
Many standards and manufacturers limit multi-leg slings to 60 degrees from vertical (a 120 degree included angle), with reduced ratings above 45 degrees from vertical. Check the rating tag and the applicable standard for your sling.