Your Ultimate Guide to Lux, Lumens and Watts

FirstWhat’s LUX? What about lumen? How do LUX differ from, lumen? How are these parameters used in the lighting industry? Well, in this guide, you will understand the real meaning of LUX and Lumen. Plus, you will understand how these expressions affect energy consumption, lighting levels, etc. Keep reading to find out how these measurements relate to each other.


OLYMPUS DIGITAL CAMERAThe level of light intensity is measured in terms of LUX. Commonly referred to as illumination, illuminance, etc., LUX will tell you the intensity of any light you intend to install. One LUX represents an illumination covering one square meter. However, the surface should be a meter away from a candle.

The SI units for lux are 1m// m^2. This is the light density per square meter. Different sources have different LUX levels.  Here is a breakdown of different sources of lights and their respective LUX levels.

  • Ambient daylight: Ambient daylight has a typical lux of between 32,000 and 100,000.
  • Direct sunlight: Direct sunlight has a typical lux of 10,000 to 25,000.
  • Overcast daylight: Overcast daylight comes with a typical lux of 1000
  • Sunset and sunrise: The typical lux of sunset and sunrise is 400.
  • Full moon: Full moon and night come with a typical lux of 1 and less than 0.001 respectively.

Lighting Lumens

lumenExpressed in quantum, lumens represent the total light packets produced by a given source of light like LED, sunlight, etc. In certain circumstances, the total measured light can be referred to as luminous flux. However, engineers use this term in commercial and industrial settings.

How Do Lumens and Lux Relate

One Lux is equal to one lumen per one-meter square. Thus, if you have 10 LUX, it means that you have 10 lumens in 10 square meters (area). This means that you need larger measured lumens to light up a large area using the same lux. To do this, simply increase the fixtures. Large commercial and industrial settings like warehouses are characterized by larger open spaces. Here, you need more high-power light fixtures.


Ratted power is commonly associated with measuring the actual power required to operate a light fitting. Its measured om Wattage. The total amount of power consumed (i.e. when it comes to the creation of a light lumen) is known as rated power.  Here are a few examples to help you understand wattage:

  • The total amount of energy used to create visible light from a lamp.
  • The heat output from a lighting spectrum
  • Parasitic power losses

Watts to Lumen

In engineering, converting electrical power (which is measured in Watts) to light (measured in Lumens) is known as luminous efficacy. Luminous efficacy is normally expressed in terms of LPW—an expression that stands for Lumens per Watt.

The Bottom-Line

what is lumensThe above guide will help you understand LUX, Lumen, as well as Watts. You will learn how these measurements affect energy consumptions and lighting levels. Plus, you will understand how these facts affect LED lighting fixtures.


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