Crane Boom Length Calculator

Inputs that control boom geometry

Enter horizontal radius and hook height from the crane pivot to the pick point. Radius drives outreach; height drives clearance. The calculator supports meters and feet, converting everything to meters internally for consistent math. Use “Allowance” to add rigging block, reeving, and clearance distance before safety is applied.

Auto angle estimation for early planning

Auto mode assumes the boom line runs directly from pivot to hook, so the base boom length is √(r²+h²). The estimated boom angle is atan(h/r). This is useful for early lift studies, crane positioning options, and checking whether a proposed setup is in the right range before you open the manufacturer chart.

Fixed angle checks against a lift plan

Fixed mode lets you test a planned boom angle. Because radius and height must both be achievable at that angle, the required length becomes max(r/cosθ, h/sinθ). This quickly flags plans where the selected angle is too shallow or too steep for the required geometry, helping you adjust the lift path or crane location.

Allowance and safety margin logic

After computing base length, the tool adds your allowance, then multiplies by the safety margin percentage. This creates a recommended boom length that includes practical field tolerances. Typical allowances range from 0.3–1.0 m (1–3 ft) depending on hook block and rigging. Safety margins are often 5–15% for planning, but follow your site procedure.

Interpreting results and limitations

The result is a geometry estimate, not a capacity approval. Always verify the final configuration using the crane load chart, reeving, parts of line, counterweight, outrigger setup, wind limits, and radius changes during the lift. If you enter a maximum boom length, the calculator reports feasibility as a simple yes/no check for the recommended value.

Record the exported summary in your lift package, including assumptions and notes. Re-check radius after setting mats and outrigger spread, and confirm the hook height reference point. For complex lifts, consider jib offsets, boom deflection, and swing clearance before final sign-off formally.

FAQs

1) What boom length does the calculator output?

It outputs base boom length, length with allowance, and a safety-adjusted recommended length in your chosen units. These values support planning and documentation, not final crane configuration approval.

2) When should I use fixed angle mode?

Use it when the lift plan specifies a boom angle or you need to test clearance at a constrained angle. The tool checks the minimum length needed to achieve both the required radius and height.

3) What should I enter as allowance?

Enter extra length for hook block, rigging, reeving, and practical clearance. If you are unsure, start with 0.3–1.0 m (1–3 ft) and adjust based on your rigging arrangement.

4) Does the result confirm lifting capacity?

No. Capacity depends on the manufacturer load chart, parts of line, counterweight, outrigger setup, wind limits, and radius variation during the lift. Always verify against the approved chart and plan.

5) Why is my recommended boom longer than expected?

Allowance and safety margin increase the base geometric length. Also, in fixed mode, a shallow angle can force a much longer boom to achieve the required height at the same radius.

6) How do CSV and PDF exports work?

CSV downloads from the server using the last calculated result stored in your session. PDF downloads in the browser using a lightweight script and includes inputs, outputs, and warnings for sharing.

This tool estimates boom length from geometry, then applies allowance and a safety margin. Always confirm final configuration using the crane manufacturer load chart, site constraints, and the lift plan approvals process.