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 Calculator

Beam Spread
Illuminance

Enter any 2 values to calculate the missing variable


Related Calculators

Beam Spread Formula

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

Variables:

  • 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

FAQ

What is beam spread in lighting design?
Beam spread refers to the width of light emitted from a source, measured at the point where the intensity of the beam falls to 50% of its maximum. It’s crucial in lighting design for determining how well an area will be illuminated.

How does the angle of a beam affect its spread?
The angle of the beam significantly influences its spread; a larger angle results in a wider beam spread. This means that the light covers a broader area but with reduced intensity at any given point compared to a narrower beam.

Why is it important to calculate beam spread accurately?
Accurate calculation of beam spread is essential for efficient lighting design. It ensures that light is distributed evenly across an area, avoiding dark spots and glare, which can be uncomfortable or hazardous.

Can beam spread be adjusted after installation?
Yes, beam spread can often be adjusted after installation, depending on the type of lighting fixture used. Many modern fixtures come with adjustable optics or lenses that allow for changes in beam spread to adapt to different lighting needs.