How to read a crane load chart

Every number in the worked examples below comes from Boom Angle's invented Practice A or Practice B. These are original teaching charts, not a manufacturer's chart or an NCCCO exam chart. They are not equipment ratings and cannot authorize a lift. Open load chart practice to follow the examples.

Start with configuration, radius and boom length

Radius is the horizontal distance from the crane's center of rotation to the vertical load line. Boom length is a different measurement; do not use boom length as a substitute for radius. Check the chart's definitions, units and configuration notes before choosing a row or column.

Our invented Practice A is labelled 360° on fully extended outriggers. Practice B is labelled over rear only on fully extended outriggers. Choosing A because it gives a larger number would ignore the configuration. In actual work, identify the exact equipment and applicable chart, including boom arrangement, support configuration, operating area and other conditions in its instructions.

✓ OSHA 1926.1417(a) and (c) address compliance with manufacturer operating procedures and availability of operating information, including rated capacities and load charts. The teaching sequence here does not replace those procedures.

Keep feet and pounds visible beside your arithmetic. An unlabeled number can quietly move from a radius entry to a weight calculation. Say the selection aloud during practice: chart name, configuration, radius row, boom column and gross capacity.

Worked lookup on invented Practice A

Suppose the training setup specifies a 25 ft radius and 70 ft main boom. Only these invented charts instruct you to select the next listed entry at or above each dimension when an exact entry is missing. Therefore:

1. Select the 30 ft radius row.
2. Select the 80 ft boom column.
3. Read 24,000 lb gross capacity from that cell.

The invented row list is 10, 20, 30, 40 and 50 ft; the column list is 40, 60, 80 and 100 ft. Do not interpolate a capacity between cells. The rounding rule belongs to these practice charts. An actual crane's instructions determine how unlisted dimensions must be handled.

A blank cell supplies no capacity. For example, the invented 40 ft boom column has no entry at 40 ft radius. Do not fill that blank using a nearby value or your own geometry. In the tool, an unavailable selection stops the calculation rather than producing a rating.

Repeat the 30 ft/80 ft lookup on invented Practice B and the gross value becomes 18,000 lb. Identical row and column labels do not make the two charts interchangeable. The chart selection remains part of the answer.

What does the bold line mean?

On our invented charts, the bold line separates cells governed by structural limitation from cells governed by stability limitation. Both are capacity limits. Neither side is permission to disregard the printed value, and the line is not a target operating point.

For invented Practice A at an 80 ft boom length, the 10 ft radius cell is 28,000 lb, structural. The 30 ft radius cell is 24,000 lb, stability. The tool deliberately labels the basis so you can practice noticing the distinction rather than treating every capacity as the same kind of limit.

✓ OSHA 1926.1433(b)(1) and (2) address load-rating requirements where stability and structural competence govern. The rule does not establish a universal visual legend for every chart. On real equipment, read that chart's own legend and notes; do not infer a limitation solely from the position of a bold line.

Gross capacity minus deductions gives net payload capacity

Continue with the invented Practice A gross capacity of 24,000 lb. Select its 600 lb hook block, 800 lb stowed jib and 400 lb rigging. These are the invented tool's deduction values, not typical equipment weights.

Step	Invented Practice A calculation
Total deductions	600 + 800 + 400 = 1,800 lb
Net payload capacity	24,000 − 1,800 = 22,200 lb
Compare a 20,000 lb payload	20,000 ≤ 22,200
Percentage of net payload capacity	20,000 ÷ 22,200 × 100 = 90.1%

The comparison means only that the invented payload is within this arithmetic limit. It is not lift approval. The percentage uses net payload capacity as its denominator; a percentage calculated against gross capacity answers a different question.

In these tools, choose either the hook block or headache ball for the selected hoist attachment, and the stated jib condition. On real equipment, follow the actual chart's deduction instructions and account for the installed and suspended components as required. Do not transfer the practice tool's simplified choices to a crane configuration.

Use the net-capacity calculator to lay out the subtraction. Recheck the source of the gross value and each deduction before accepting a total; a calculator checks arithmetic, not configuration suitability.

Keep chart reading within the full job requirements

✓ OSHA 1926.1404 covers assembly and disassembly requirements, including the configuration and support issues addressed by that section. Those responsibilities cannot be replaced by a load-chart exercise. Read it alongside 1926.1417 and 1926.1433 when studying the regulatory framework.

For study, log mistakes as wrong chart, wrong row or column, overlooked note, missed deduction or arithmetic error. Repeat the underlying step with a different invented setup. Read the Core written guide and certification requirements, then use the written diagnostic to choose your next study priorities.

Sources

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• 29 CFR 1926.1417: Operation, OSHA, paragraphs (a) and (c). Retrieved 17 Oct 2026.
• 29 CFR 1926.1404: Assembly/Disassembly, OSHA. Retrieved 17 Oct 2026.
• 29 CFR 1926.1433: Design, Construction and Testing, OSHA, paragraph (b). Retrieved 17 Oct 2026.
• Boom Angle practice tool, original invented Practice A and B data and calculation rules, checked 17 Oct 2026. All worked values above use that teaching model.