How to use this calculator
- Enter total load. Include the lifted item and any rigging weight carried by the two pick points.
- Enter pick span. Measure the distance between the left and right pick points along the load.
- Locate the COG. Enter the horizontal distance from the left pick point to the center of gravity.
- Set legs, angles and WLL. Enter the loaded sling legs, angle from horizontal and per-leg WLL for each side.
- Review the limiting side. Compare pick loads, leg tension and WLL utilization before moving to a lift plan.
How it works
Static two-pick load share follows moment balance about the opposite pick:
R_left = W x (L - x) / L R_right = W x x / L
where L is the pick point span and x is the
center-of-gravity distance from the left pick point.
Once each pick load is known, each side uses the same sling-angle relation: T = R / (n x sin(theta)) For a pure angle-factor screen, use the sling angle load calculator. For cable stretch after the load is known, use the wire rope stretch calculator.
Worked example
Verified against the live calculator
A 2,000 lbf load has pick points 8 ft apart
and the COG is 3 ft from the left pick. The left side carries
2,000 x (8 - 3) / 8 = 1,250 lbf; the right side carries
750 lbf. With one leg per side at 60 deg,
the left leg tension is about 1,443 lbf and the right
leg tension is about 866 lbf.
Frequently asked questions
How do you calculate pick-point load from center of gravity?
For two pick points, left reaction is R_left = W x (L - x) / L and right reaction is R_right = W x x / L, where W is total load, L is pick span and x is the COG distance from the left pick.
Why does the closer pick point carry more load?
The pick point closer to the center of gravity has the shorter lever arm to the load and therefore carries a larger share of the total weight in a static two-pick balance.
How does this differ from the sling angle calculator?
This calculator finds left and right pick loads first. The sling angle calculator assumes one total load share. Use this when the COG is not centered between two pick points.
Can this approve an actual lift?
No. This is a static worksheet. Real lifts need verified weight and COG, qualified rigging review, sling and hardware ratings, hitch factors, edge protection, stability and dynamic effects.
Method & assumptions
- The load is modeled as a static two-pick system with the center of gravity between the pick points.
- Pick loads are vertical reactions; sling-leg tension then applies the entered angle and loaded-leg count per side.
- Side-to-side, fore-aft and out-of-plane center-of-gravity offsets are not modeled.
- Unequal sling lengths, load tilt, spreader beams, shackles, lugs, basket/choker reductions, D/d, edge protection and dynamic factors are not modeled.
- Use verified weights, measured COG, manufacturer data and qualified rigging review for final lifting decisions.