Crane Load Calculator

Load moment = load weight × working radius (t·m). It represents the overturning force on the crane. Exceeding rated load moment is the primary cause of crane tipping accidents.

Working radius = boom length × cos(boom angle from horizontal). Or measure the horizontal distance from crane center to load directly.

Keep utilization below 85% of the load-chart rated capacity for normal lifts, below 75% for critical lifts (over people, expensive equipment, complex rigging). Never exceed 100%.

No. This tool computes geometry (radius, angle, load moment) and compares your load against the rated capacity you enter from the manufacturer's load chart. It never estimates crane capacity on its own — always have a qualified person verify all lifts against the actual load chart.

A load chart is the manufacturer's table of rated lifting capacities for a specific crane at different boom lengths and working radii. It is specific to the crane model, configuration (boom length, counterweight, outrigger spread), and wind conditions. Find your working radius row, read across to your boom length column — that intersection is rated capacity.

Longer boom lengths reduce rated capacity at any given radius because the heavier, longer boom increases overturning moment even without changing the load. For a given load and radius, use the shortest boom that can safely reach the pick and set points.

Subtract the weight of the hook block, headache ball, all rigging hardware (shackles, slings, links), and any spreader beam from the load-chart rated capacity. The net figure is the maximum payload you can safely lift.

A critical lift is typically defined as any lift exceeding 75–85% of crane rated capacity, a tandem (multi-crane) lift, a lift over energized equipment or personnel, or a lift in a confined space. Critical lifts require a documented lift plan reviewed and signed by a qualified person or engineer before the lift begins.