Enter the load and the radius (with selectable units) into the calculator to compute a simplified, hypothetical boom-length estimate using the rule-of-thumb shown below. This tool is intended for educational/illustrative use only and must not be used as a substitute for manufacturer crane load charts, jobsite lift planning, or engineering review (real lifts depend on crane model/configuration, required hook height, boom angle, jib use, parts of line, counterweights, deratings, ground conditions, and more).

Boom Length (Simplified) Calculator

Enter any 2 values to calculate the missing variable (simplified model, not a load chart)

Boom Length Formula

The following simplified, hypothetical formula is used in the calculator above. It is not a crane load-chart method and it does not account for required hook height, boom angle, jib use, crane configuration, or manufacturer deratings.

BL = R \times \left(1 + \frac{L}{L_{ref}}\right), \quad L_{ref}=10~\text{short tons}

Variables:

  • BL is the boom length (same length units as R; the calculator converts internally to meters)
  • L is the load (the calculator converts the entered load to short tons internally)
  • R is the radius (same length units as BL; the calculator converts internally to meters)
  • Lref is the reference load used by this simplified model (10 short tons)

To calculate the boom length in this simplified model, multiply the radius by the sum of 1 and the ratio of load to the reference load. For real crane planning, always use the manufacturer’s load charts and proper lift planning procedures.

What is Boom Length?

Boom length is the length of a crane’s boom (the main lifting arm, which may be telescopic or lattice) measured along the boom from its base/heel area to the boom tip. Boom length affects the crane’s possible reach and achievable hook height, but selecting a safe configuration requires considering the full lift geometry and the crane’s rated capacities from manufacturer load charts.

How to Calculate Boom Length?

The following steps outline how this page’s simplified model calculates the Boom Length.

  1. Determine the load (L) to be lifted (enter as short tons or metric tons).
  2. Determine the radius (R) from the crane’s center of rotation to the load (enter in meters/feet/yards).
  3. Use the hypothetical formula above: BL = R × (1 + L / Lref), where Lref = 10 short tons (the calculator converts units internally as needed).
  4. Calculate the Boom Length (BL) in your chosen length unit.
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Load (L) = 5 short tons

Radius (R) = 10 meters