The best way to find the load capacity of a crane is to consult its load chart , which is provided by the manufacturer and usually found in the crane's operator manual or cab. This load chart shows the crane's load capacity at different boom lengths, boom angles, and load radii (the horizontal distance from the crane's rotation center to the load). The load capacity usually decreases as the boom length or load radius increases. To determine the load capacity:

1. Calculate the load radius, which depends on the boom length and angle.
2. Find the corresponding lifting capacity on the load chart for that radius and configuration.
3. Take into account environmental and operational factors such as ground conditions, wind speed, and whether the crane’s outriggers or stabilizers are deployed.
4. Consider counterweights and whether the capacity is indicated for lifting over the front, rear, or a 360-degree rotation.

Modern cranes also often have load moment indicators (LMI) or rated capacity indicators (RCI) that provide safety warnings when loads approach the crane's limits. However, understanding and correctly using the load chart is essential for safe and effective crane operation.