Crane Lifting Capacity Calculator

Inputs

Formula Used

This tool combines a chart-based rated capacity with reduction factors, then compares it to the total lifted load.

• Total Load = Load Weight + Rigging Weight + Hook Block Weight
• Load Moment = Total Load × Operating Radius
• Adjusted Capacity = Rated Capacity × (Lift Factor × Setup Factor × Dynamic Factor × Wind Factor × Radius Accuracy Factor)
• Utilization (%) = (Total Load ÷ Adjusted Capacity) × 100

Always confirm values against the manufacturer load chart, site method statement, and competent supervision.

How to Use This Calculator

1. Read your crane load chart for the exact configuration.
2. Enter the rated capacity and your planned operating radius.
3. Enter load, rigging, and hook block weights to get total load.
4. Select lift category, setup condition, and dynamic condition.
5. Add wind speed to apply a conservative wind reduction.
6. Press Calculate and review utilization, status, and notes.
7. Download CSV or PDF for lift planning and briefings.

Example Data Table

Examples are illustrative; use manufacturer data for real lifts.

Professional Guide to Crane Lifting Capacity

1) Why lifting capacity changes with radius

Crane capacity is governed by overturning moment, not only hook load. As radius increases, the same load creates a larger moment (Moment = Load × Radius). For example, a 20 t lift at 8 m creates about 160 t·m, while at 12 m it becomes about 240 t·m. This is why load charts drop quickly as radius grows.

2) Rated capacity comes from the manufacturer chart

The “Rated capacity” input should be taken directly from the correct chart page for your crane configuration: counterweight, boom length, jib, parts of line, and outrigger or tire condition. Do not interpolate casually; if your planned radius sits between chart points, select the more conservative value.

3) Total load must include rigging and hook block

Field incidents often come from underestimating non-payload weight. Typical rigging may add 0.2–1.5 t depending on spreaders, shackles, and sling sets. Hook blocks can add 0.3–2.0 t on larger cranes. This calculator sums payload, rigging, and hook block so utilization reflects the real lifted mass.

4) Utilization targets support safer planning

Many lift plans set a working target below 100% to allow for tolerances, small radius drift, and operational variability. Common planning thresholds are 75–85% for routine lifts and lower for complex picks. The “Target utilization” field flags CAUTION before the lift reaches the hard limit.

5) Wind is a measurable risk factor

Wind adds side loading, increases sail area effects, and can amplify dynamic motion. Site procedures often specify maximum wind speeds for particular loads and crane types. This calculator applies a conservative reduction band: no reduction below about 9 m/s, then 10–30% reductions as winds rise. Always follow the stricter site limit.

6) Dynamic effects and shock loading

Rapid hoisting, sudden slewing, snagging, or traveling with a suspended load can create transient loads above the static weight. Even a modest dynamic allowance can materially change the outcome near chart limits. Choose a dynamic condition that matches the lift method, or enter a custom factor when engineering guidance exists.

7) Setup condition drives stability

Outriggers fully deployed typically provide the best stability and chart capacity. Partial outriggers or lifting on tires reduces stability and may switch you to a different chart entirely. This calculator applies conservative setup factors to highlight how sensitive capacity can be to ground conditions and configuration accuracy.

8) Documenting a lift for clear communication

A practical lift package should include the chart reference, load breakdown, radius and boom data, wind conditions, roles and signals, exclusion zones, and contingency steps. Use the CSV or PDF output to support briefings and toolbox talks so everyone sees the same numbers and assumptions.

FAQs

1) What does “Rated capacity” mean here?

It is the manufacturer chart capacity for your exact configuration and radius. Enter the conservative chart value that matches your counterweight, boom, jib, and setup condition.

2) Why does the calculator reduce capacity?

Reductions account for lift category, setup confidence, dynamic effects, and wind. They provide conservative planning margins, but they do not replace engineered lift plans or manufacturer limits.

3) Should I include below-hook devices?

Yes. Spreaders, lifting beams, clamps, and any accessories must be included in rigging weight. If unsure, weigh the assembly or use certified data from the supplier.

4) What if boom and radius do not match?

If the entered radius differs from boom × cos(angle) by more than 5%, the tool applies added conservatism. Recheck setup geometry, pick point location, and measurement method.

5) When is a lift considered “critical”?

Criteria vary by site, but common triggers include high utilization, lifts over live plant, tandem picks, limited clearances, or unusual rigging. Follow your project lifting procedure and approvals.

6) Can this replace a full lift plan?

No. It supports quick checks and documentation, but a competent person must confirm chart applicability, ground bearing, rigging design, wind limits, and communication controls.

7) What is a safe utilization target?

Many teams plan routine lifts at 75–85% and lower for complex operations. Use your site policy and engineering guidance, especially for dynamic lifts or high-wind conditions.