Confirm the symmetric arrangement
This model requires two equal legs with the load centred between them. Use a different load-distribution model for an offset centre of gravity.
LIFTING & RIGGING / TOOL 08
Two-Leg Sling Angle and Tension Calculator
Use this to see how sling inclination changes ideal static tension in two equal legs supporting a centred load.
Before you start: required inputs
- Find the complete mass supported below the two sling legs, including any load-mounted accessories.
- Measure each leg’s angle above a horizontal line in the proposed symmetric arrangement.
Calculation diagram
A PRACTICAL WALKTHROUGH
How to use this calculator
Measure the angle from horizontal
A vertical leg is 90°. Do not use the angle from vertical or the included angle between the two legs.
Read tension at each leg
Compare configurations using the calculated leg action and horizontal connection force. Select actual slings using their applicable ratings and conditions separately.
5,000 kg load with legs at 60° above horizontal
THE INPUTS
Complete supported mass 5,000 kg; each sling leg 60° above horizontal.
THE RESULT
Ideal static tension is 28.3094 kN per leg. Each lower connection has a horizontal force of 14.1547 kN; the included angle is 60°.
What does the result mean?
01
The two vertical tension components add to the complete static weight; the tension itself is higher than the vertical share when the legs are inclined.
02
Reducing the angle above horizontal increases leg tension and horizontal force at the load connections.
03
Calculated tension is an action, not a sling working load limit or a recommended sling size.
Watch for this
Entering an angle measured from vertical. For a leg 30° from vertical, the angle required here is 60° above horizontal.
Formula & model conditions +
W = mass × 9.80665
Tension per leg = W / [2 × sin(angle above horizontal)]
Horizontal force at each lower connection = T × cos(angle)
- Two equal sling legs, symmetric geometry, a centred load and ideal static equilibrium are assumed.
- The entered mass includes everything supported by the two sling legs. Sling self-weight is neglected.
- Calculated leg tension is an action, not a sling working load limit; sling ratings, connection geometry, dynamics and angle restrictions need separate checks.
Common questions
Can this calculate a four-leg sling?
No. Four-leg load sharing depends on arrangement and the applicable rating method; equal sharing among four legs must not be assumed from this two-leg model.
Why are the horizontal forces reported?
Inclined slings apply inward horizontal force at the lower connections. The lifting points and load structure need to accommodate those forces separately.