Beam Spread

Light Bulb Beam Angle - Common terms in selecting a light bulb are "Flood" light or "Spot" light. These are designations of beam angle. The beam angle is the degree of width that light emanates from a light source. Specifically: The angle between those points on opposite sides of the beam axis where the intensity drops to 50% of maximum.

Typically a narrow beam angle is a 'spot' of light and a broader beam angle 'floods' an area with light, called a flood light. There are a number of much more specific designations of beam angle. They are not used consistently between all the light bulb manufacturers, but several use this general terminology:

  • Narrow Spot: 05-15 degrees
  • Spot: 16-22 degrees
  • Narrow flood: 23-32 degrees
  • flood: 33-45 degrees
  • wide flood: 45+ degrees