Load Details
Enter hook block, shackles, slings, spreader beams and other lifting gear in kilograms. The calculator converts these values to tonnes automatically.
Crane Load Chart Capacity
Boom length and boom angle are recorded to match the crane load chart configuration. They do not calculate crane capacity. Always enter the rated capacity from the manufacturer load chart for the exact crane setup.
Distance from crane centreline to the load at the pick-up position.
Capacity copied from the crane load chart for the pick-up radius and exact crane setup.
Distance from crane centreline to the load at the final landing or working position.
Capacity copied from the crane load chart for the working radius and exact crane setup.
The rigger must measure each radius and then enter the rated crane capacity from the manufacturer load chart for that exact radius, boom length, boom angle, counterweight, outrigger setup and crane configuration. This calculator does not calculate crane capacity from radius.
Safety Note
Enter parameters and calculate to see results.
What Is a Crane Lift Study Calculator?
A crane lift study calculator is a critical planning tool used by riggers, crane operators, and site supervisors. It helps compare the total lifted load against the crane's rated capacity at both the initial pick-up radius and the final working radius.
By evaluating these two points, the calculator determines the overall capacity percentage, ensuring the crane stays safely within its manufacturer-specified operating limits throughout the entire swing path.
Why Rated Crane Capacity Must Be Entered
A crane does not have one fixed lifting capacity. Its safe working capacity changes with radius, boom length, counterweight, outrigger setup and crane configuration. The farther the load is from the crane centreline, the lower the available lifting capacity normally becomes. This calculator therefore compares the total lifted load against the rated crane capacity at both the pick-up radius and the working radius. The highest capacity used controls the overall lift status.
Why Boom Length and Boom Angle Matter
Boom length and boom angle help identify the exact crane configuration used for the lift study. A longer boom or lower boom angle normally reduces available lifting capacity, but this calculator does not estimate crane capacity from geometry. The rigger must enter the rated capacity from the manufacturer crane load chart for the exact boom length, radius, counterweight and outrigger setup.
Why the Rated Capacity Must Be Entered Manually
Two cranes with the same radius can have very different capacities depending on boom length, boom angle, counterweight, outrigger setup, fly jib, ground condition and manufacturer limits. For this reason, the calculator only checks the lifted load against the rated capacities entered by the rigger.
Why Radius Alone Does Not Decide Capacity
The rigger or lift planner must use the correct manufacturer load chart for the exact crane model being used. Entering only a radius into a calculator cannot determine capacity because different cranes (even of the same tonnage class) have different boom weights, outrigger spans, counterweight configurations, and structural limits. Always refer to the exact OEM load chart to find the capacity for your measured radius.
Why Approach Warnings Begin Above 90%
Approach warnings commonly begin above 90% of rated capacity. This calculator marks 90–97.5% as approaching rated capacity, 97.5–100% as critical, and anything over 100% as STOP because it exceeds the rated crane capacity entered by the rigger.
Why Radius Matters
In crane operations, capacity is directly tied to the working radius (the horizontal distance from the crane's centre of rotation to the centre of gravity of the load).
- As the boom extends or lowers to reach further away, the crane's lifting capacity reduces significantly due to leverage and tipping forces.
- Even a small increase in radius (for example, drifting a load outwards to clear an obstacle) can cause the capacity to drop below the weight of the load, risking a structural failure or a tip-over.
What Must Be Included in Total Lifted Load
The crane must lift everything hanging from the boom tip, not just the object being moved. The total lifted load must include:
Common Mistakes
Planning Note
This calculator provides planning estimates only. Always verify results against the exact crane model, boom length, counterweight, outrigger setup, ground conditions, site rules, and manufacturer load chart before executing any lift.