Crane Lift Capacity Calculator

Example Load Chart Table

This table is an example dataset for demonstrating the calculator workflow. Real capacities vary by manufacturer, boom configuration, counterweight, and operating mode.

Formula Used

The calculator compares an adjusted gross load against an adjusted allowable capacity. Rated capacity must come from your applicable crane chart for the selected boom length and radius.

• DynamicFactor adds conservatism for acceleration, swing, and handling.
• WindFactor reduces capacity at higher wind speeds.
• SlopeFactor reduces capacity when the crane is not perfectly level.
• SafetyMargin derates the rating to support planning.

How to Use This Calculator

1. Read your crane load chart for the planned boom length and radius.
2. Enter the rated capacity exactly as shown in your chart.
3. Enter load, rigging, and hook block weights in your chosen unit.
4. Set dynamic factor and site conditions (wind, slope, outriggers).
5. Submit to view utilization, margin, and exportable results.

Practical Notes

• Always account for boom angle, counterweight, parts of line, and attachments.
• Keep radius realistic; small radius changes can impact capacity heavily.
• For critical lifts, follow your project lift plan and approval process.
• Do not exceed local regulations or manufacturer operational limits.

If you need manufacturer-specific chart lookup, consider adding your crane model charts as a selectable dataset.

Input Data Quality and Chart Selection

Start by selecting the correct chart line for your crane configuration. Use the boom length, counterweight, parts of line, and operating mode shown on the manufacturer chart. Enter the rated capacity at the planned radius; a 0.5 m radius increase can reduce capacity by several percent. Measure radius from center of rotation to hook line; record units.

Adjusted Gross Load Components

Gross load is more than the object weight. Add rigging, shackles, spreader beams, lifting beams, and the hook block. The calculator then applies a dynamic factor to cover starting, stopping, and controlled swing. For routine lifts, 1.05–1.15 is common; complex picks may justify 1.20 within your procedures.

Site Condition Derating Factors

Environmental and setup conditions reduce usable capacity. Wind derating steps down after 20 km/h, and the tool applies stronger reductions beyond 30 and 40 km/h. Ground slope affects stability; values above 3° should trigger re-leveling or engineered mats. Outrigger selection is a major driver: full extension typically outperforms partial or on-tyres picks. Side pull is treated as a 15% reduction, and heavy or continuous duty further derates planning capacity.

Utilization and Margin Interpretation

Utilization compares adjusted gross load to adjusted allowable capacity. Under 85% supports comfortable planning, 85–100% requires tighter controls, and above 100% indicates the configuration is not acceptable. Margin shows remaining capacity or overage in your selected unit and helps set a target payload when only rigging changes. The lift category margin intentionally derates: standard uses 0.85, while critical uses 0.75 for conservatism.

Reporting and Documentation Outputs

A lift plan is stronger when calculations are traceable. The CSV export captures inputs and results for spreadsheets and approvals. The PDF export creates a one-page summary suitable for attachments. Use the notes field to document tandem lifts, restricted swing, and exclusion zones so reviewers see assumptions clearly. Re-run the calculation if any field changes, and archive exports with the permit and toolbox talk record.

FAQs

1) Does this replace the manufacturer load chart?

No. Use it to check gross load and planning margins after you select the correct rated capacity from your chart. Always follow site procedures, permits, and lift supervisor approval.

2) Which capacity should I enter?

Enter the chart rating that matches boom length, radius, counterweight, and operating mode. If the chart lists multiple parts of line or jib options, choose the exact configuration planned.

3) What should I use for dynamic factor?

Many teams use 1.05–1.15 for steady lifts. Increase for fast handling, swinging, or uncertain control, and reduce only when strict slow-speed controls are enforced. Follow your company method statement.

4) How does wind affect the result?

The tool applies step-down factors after 20 km/h, with stronger reductions above 30 and 40 km/h. Treat this as conservative planning; always follow the manual limits for wind, sail area, and accessories.

5) What if utilization is above 100%?

Stop and redesign the lift: reduce radius, reduce payload, improve setup (full outriggers, better mats, level ground), or select a higher-capacity crane. Do not proceed until utilization is within limits per your plan.

6) Can I share the calculation with my team?

Yes. Run the calculation, then use CSV for spreadsheets or the PDF summary for approvals. Include notes about assumptions, rigging, and constraints so reviewers can validate the inputs quickly.