Wire Rope & Rigging SWL Calculator
Enter sling configuration, rated SWL, and angle from vertical to get safe working load per leg accounting for the sling angle factor. Danger zone warning at angles over 60°. Nothing uploaded.
Rigging Configuration
Safe Working Load
IMPORTANT: This tool is for reference and education only. All lifting operations must be designed and supervised by a competent rigging engineer. Never exceed the SWL of any component in the lift. Angles below 30° from vertical (above 60° from horizontal) should be avoided.
Learn more: Rigging angles and load distribution
How sling angle affects safe working load
As the angle of a sling increases from vertical, the tension in each leg increases beyond what it would carry in a straight pull. At 30 degrees from vertical, each leg carries 1.15x the load. At 45 degrees, it is 1.41x. At 60 degrees, each leg carries exactly twice the load it would in a straight vertical pull. This is why rigging standards prohibit sling angles greater than 60 degrees from vertical without engineering approval.
Safe rigging practices and sling angle factor
The sling angle factor is the multiplier applied to the load per leg due to geometry. It equals 1/cos(θ) where θ is the angle from vertical. The effective safe working load of each leg is the rated SWL divided by the angle factor. Most rigging standards recommend a maximum sling angle of 60 degrees from vertical (30 degrees from horizontal), with preference for angles below 45 degrees from vertical.
FAQ
How does sling angle affect safe working load?
As the angle of a sling increases from vertical, the tension in each leg increases beyond what it would carry in a straight pull. At 30° from vertical, each leg carries 1.15x the load. At 45°, it is 1.41x. At 60°, it is 2.0x - meaning each leg must support twice the load it would at zero angle. This is why rigging standards prohibit sling angles greater than 60° from vertical without engineering approval.
What is the sling angle factor?
The sling angle factor is the multiplier applied to the load per leg due to the geometry of the sling. It equals 1/cos(θ) where θ is the angle from vertical. At 0° (straight down), the factor is 1. At 45°, it is 1.414. At 60°, it is 2.0. The effective SWL of each leg is therefore the rated SWL divided by the angle factor.
What is the maximum safe sling angle?
Most rigging standards (ASME B30.9, EN 13414) recommend a maximum sling angle of 60° from vertical (30° from horizontal). At this angle, each leg carries exactly twice the load of a straight pull. Below 45° from vertical is preferred for general lifting. Angles above 60° from vertical require specific engineering approval.