Enter the distance to the surface (in) and the angle of the beam (radians) into the Calculator. The calculator will evaluate the Beam Spread. 

Beam Spread Formula

BS = 2*D*tan(A*.5)


  • BS is the Beam Spread (in)
  • D is the distance to surface (in)
  • A is the angle of the beam (radians)

To calculate Beam Spread, multiply the distance to the surface by 2, then multiply by the tangent of half the beam angle.

How to Calculate Beam Spread?

The following steps outline how to calculate the Beam Spread.

  1. First, determine the distance to surface (in). 
  2. Next, determine the angle of beam (radians). 
  3. Next, gather the formula from above = BS = 2*D*tan(A*.5).
  4. Finally, calculate the Beam Spread.
  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.

distance to surface (in) = 30

angle of beam (radians) = 14