Enter the expected depreciation into the Calculator. The calculator will evaluate the Light Loss. 

Light Loss Formula

LLF = 1 - ED


  • LLF is the Light Loss ()
  • ED is the expected depreciation

To calculate Light Loss, subtract the expected depreciation from 1.

How to Calculate Light Loss?

The following steps outline how to calculate the Light Loss.

  1. First, determine the expected depreciation. 
  2. Next, gather the formula from above = LLF = 1 – ED.
  3. Finally, calculate the Light Loss.
  4. 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.

expected depreciation = 0.809


What is expected depreciation in the context of lighting?

Expected depreciation in lighting refers to the decrease in light output or luminous flux over time. It is a measure of how much the brightness of a light source diminishes due to factors such as aging, wear, and environmental conditions.

How can understanding light loss benefit lighting design?

Understanding light loss is crucial for lighting design because it helps in selecting lighting systems that maintain adequate illumination over their lifespan. It ensures that spaces remain well-lit, safe, and functional, even as the lighting fixtures age.

Are there any common factors that contribute to the depreciation of light output?

Yes, several factors contribute to the depreciation of light output, including lamp lumen depreciation, fixture dirt depreciation (accumulation of dust and dirt on fixtures), and room surface dirt depreciation (accumulation of dust and dirt on room surfaces reflecting light).

Can the Light Loss Formula be applied to all types of lighting technologies?

While the Light Loss Formula (LLF = 1 – ED) is a fundamental concept, its application might vary slightly across different lighting technologies due to their unique characteristics and depreciation behaviors. However, it provides a basic framework for understanding light loss in most lighting systems.