What is Beam Spread

As the light beam moves away from the surface it is directed at or when the beam width is increased, it naturally spreads out and its intensity decreases. This phenomenon can be observed when using a torch and adjusting its distance from a wall, as the spread and intensity of the light will vary accordingly.

The measurement of beam spread refers to the diameter of the light projected onto the subject. To put it simply, if you were to shine a flashlight on a wall, the width of the illuminated circle would represent the beam spread. This measurement is typically expressed in feet. In the context of this discussion, we define beam spread as the area that receives 50% of the light power.

Flood lights typically have a beam spread ranging from over 45 degrees to approximately 120 degrees. Nevertheless, it is worth noting that certain lights advertised as floods may have a narrower beam angle of around 25 degrees. If you specifically require a light with such a narrow beam, it may be more suitable to consider spotlights instead.

Overlapping beam angles are important to ensure that the entire space is adequately illuminated, reducing the risk of accidents. For ceilings with a standard height of approximately 7.9 to 8.9 feet, a wider beam angle of 60 degrees or more is suitable. However, if your ceiling height exceeds 8.9 feet, a narrower beam angle of 45 degrees or less will be necessary.

Light spreads out in a similar manner to how butter spreads from a gun. In other words, as light moves away from a point source, its intensity decreases due to its increased dispersion (similar to the decreased thickness of butter).