Load calcs

Load calculations in rigging

Load calculations are an essential aspect of rigging to ensure the safe and effective lifting and moving of loads. These calculations involve determining the forces and stresses acting on rigging components and equipment to ensure they can handle the intended load without failure. Here are the key steps involved in load calculations in rigging:

Determine the load weight

The first step is to determine the weight of the load that needs to be lifted or moved. This can be done by directly measuring the load or obtaining the weight from load specifications or documentation.

Identify the load center of gravity

It is crucial to identify the center of gravity of the load, as it determines the balance and stability during lifting operations. The center of gravity may not always align with the geometric center of the load, especially for irregularly shaped or asymmetrical loads.

Determine the load distribution

Understand how the load will be distributed among the rigging equipment. This includes considering the number and arrangement of slings, cables, or other lifting devices, as well as the angles at which they are attached to the load. Proper load distribution ensures that the weight is evenly spread across the rigging system.

Calculate the total load

The total load to be supported by the rigging system is calculated by considering the weight of the load and the load distribution. This calculation accounts for any additional forces resulting from factors such as acceleration, deceleration, wind, or dynamic loading.

Determine rigging equipment capacity

Review the specifications and manufacturer’s recommendations for the rigging equipment being used, such as ropes, slings, shackles, and hoists. Consider the load ratings, working load limits (WLL), and safety factors provided by the manufacturer. Ensure that the rigging equipment is rated to handle the calculated total load.

Consider environmental factors

Environmental factors, such as wind, temperature, and ground conditions, can affect the stability and safety of the lifting operation. Evaluate these factors and make necessary adjustments or precautions in the load calculations.

Apply safety factors

Safety factors are additional factors of safety that are applied to account for uncertainties, unexpected loads, and dynamic forces. The safety factors depend on industry standards, regulations, and the specific circumstances of the rigging operation. Common safety factors range from 3:1 to 10:1, depending on the level of risk involved.


It is important to note that load calculations in rigging should be performed by trained and experienced professionals who have a deep understanding of rigging principles, safety standards, and the characteristics of rigging equipment. Accurate load calculations are essential to prevent overloading and ensure the safety of personnel, equipment, and the surrounding environment during lifting operations.

Materials for this article were gathered from various public sources or written by riglab.org editors.
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