Calculator Inputs
Formula Used
- Moment Based Capacity = Rated Moment ÷ Working Radius
- Adjusted Moment Capacity = Moment Based Capacity × (Condition Factor ÷ 100)
- Gross Allowable Capacity = minimum of Chart Capacity, Maximum Crane Capacity, and Adjusted Moment Capacity
- Total Deductions = Hook Block Weight + Rigging Weight + Accessory Weight
- Net Allowable Payload = Gross Allowable Capacity − Total Deductions
- Utilization = (Actual Load ÷ Net Allowable Payload) × 100
- Remaining Margin = Net Allowable Payload − Actual Load
How to Use This Calculator
- Choose metric or imperial units before entering values.
- Enter the crane name and boom length for lift documentation.
- Input the actual working radius for the planned pick.
- Enter the rated moment and the chart capacity for that exact radius and boom configuration.
- Enter the crane maximum capacity, then add hook block, rigging, and accessory weights.
- Enter the actual payload only, without duplicating deductions already listed above.
- Set the condition factor to reflect your planning reduction.
- Submit the form and review net allowable payload, utilization, graph, and export files.
Example Data Table
| Crane | Boom Length | Radius | Chart Capacity | Total Deductions | Net Allowable | Actual Load | Utilization | Status |
|---|---|---|---|---|---|---|---|---|
| Site Crane A | 30 m | 12 m | 16.00 tonnes | 1.80 tonnes | 14.20 tonnes | 10.00 tonnes | 70.42% | Comfortable working range |
| Yard Crane B | 28 m | 15 m | 12.50 tonnes | 1.30 tonnes | 10.22 tonnes | 9.40 tonnes | 91.98% | Near operating limit |
These examples show planning comparisons only. Always match the exact crane chart, boom length, configuration, and site setup.
Frequently Asked Questions
1. What does working radius mean in this calculator?
Working radius is the horizontal distance from the crane’s center of rotation to the load’s center of gravity. A larger radius usually reduces allowable lifting capacity.
2. Why does the tool ask for chart capacity and rated moment?
Both values help compare practical chart limits with a moment-based estimate. The final gross allowable capacity uses the lowest governing value.
3. Should hook block and rigging be included in the actual load field?
No. Enter hook block, rigging, and accessories in their own fields. The actual load field should represent the payload being lifted.
4. What does the condition factor do?
The condition factor reduces the moment-based capacity for planning conservatism. It can reflect operating caution, site uncertainty, or internal lift planning rules.
5. Can this replace the manufacturer load chart?
No. This page is a planning aid only. The manufacturer chart, crane computer, and approved lift plan remain the controlling references.
6. Why can the status change even when the chart capacity looks high?
Deductions, structural limits, reduced conditions, and actual payload all affect the final net allowable value. High chart capacity alone does not guarantee a safe margin.
7. Is boom length directly changing the calculation here?
Boom length is included for lift documentation and reporting context. Final crane capacity should still come from the chart for that exact boom and setup.
8. What should I do when utilization is above 100%?
Stop and revise the plan. Reduce payload, reduce radius, lower deductions, improve configuration, or choose equipment with greater available capacity.