How does sling angle affect capacity?

As the sling angle from vertical increases, the effective load capacity decreases. At 60° from vertical, capacity is only 50% of the rated WLL.

What is the minimum safe sling angle?

Never use slings at angles greater than 60° from vertical. Below this the sling tension increases dramatically and may exceed the rated capacity.

How do I calculate load per sling leg?

For symmetric lifts: load per leg = total load / (number of legs × cos(angle)). The angle factor accounts for the cosine reduction.

What is the difference between WLL and SWL?

WLL (Working Load Limit) has replaced SWL (Safe Working Load) in modern standards. Both represent the maximum load a sling should carry in normal use.

Do all sling legs share the load equally?

Only for symmetric lifts with equal leg lengths and angles. In practice, assume only 2 of 4 legs carry the load unless all legs are demonstrably equal.

Free Engineering Tool #217

Sling Capacity at Angle Calculator

Calculate the effective working load limit (WLL) of a sling at various angles from vertical. Supports 1–4 leg slings.

WLL × cos(θ)1–4 LegsRigging

Results

Effective WLL (assembly)

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Angle Factor

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Tension per Leg

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Sling Configuration

Sling Angle Factor

Angle from vertical	Factor (cos θ)	% of WLL
0°	1.00	100%
15°	0.97	97%
30°	0.87	87%
45°	0.71	71%
60°	0.50	50%

⚠️ Warning: Never use slings at angles greater than 60° from vertical. For 4-leg slings, use the 3-leg factor (assume one leg carries no load) unless all legs are verified to share load equally.

Sling Capacity at Angle Calculator | Free WLL Tool

Published by Nikolai Shelkovenko on February 15, 2026 March 5, 2026

Results

Sling Angle Factor