What Are Lumens And Kelvins? Difference And Importance Of Each

Lumens (lm) are a unit of measurement used to describe the total amount of visible light emitted by a light source. In other words, lumens measure the brightness of a light source, as perceived by the human eye.

Lumens are a more accurate measurement of the amount of light emitted by a bulb or other light source than wattage, which only measures the amount of energy consumed by the bulb. Different types of light sources can emit different amounts of light per watt, so lumens provide a more consistent and reliable measure of brightness across different types of bulbs and light fixtures.

For example, a standard 60-watt incandescent bulb typically emits around 800 lumens of light, while a 100-watt bulb emits around 1600 lumens. LED bulbs can also be rated in lumens, and many LED bulbs are designed to emit the same amount of light as traditional incandescent bulbs while using less energy.

Kelvin is the unit of measurement for temperature in the International System of Units (SI). It is named after the British physicist and engineer, William Thomson, 1st Baron Kelvin, who proposed the absolute temperature scale in 1848. Kelvin is defined as the fraction 1/273.16 of the thermodynamic temperature of the triple point of water.

The triple point of water is the temperature and pressure at which water coexists in all three phases: solid, liquid, and vapour, in equilibrium. The kelvin scale starts at absolute zero, which is the theoretical temperature at which all matter has zero thermal energy. One kelvin is equal to one degree Celsius, but the two scales differ in their starting points.

What Is The Difference Between Lumens, Kelvins And Watts?

ParameterUnit of measurementDefinition
Lumenslm (Lumens)A measure of the total amount of visible light emitted by a light source in all directions. The higher the lumens, the brighter the light.
KelvinsK (Kelvin)A measure of the colour temperature of a light source. The higher the Kelvins, the cooler or bluer the light. The lower the Kelvins, the warmer or yellower the light.
WattsW (Watts)A measure of the amount of energy consumed by a light source. The higher the watts, the more energy the light source consumes.

Is There Any Correlation Between Lumens And Kelvin? 

  • Yes, there is a correlation between Lumens and Kelvin. Both measures are related to the quality and quantity of light emitted by a light source, and they are often used together to provide a more accurate description of the light source.
  • The Kelvin rating of a light source describes its colour temperature, which can affect the perceived brightness of the light. For example, a cool white light with a higher Kelvin rating will appear brighter than a warm white light with a lower Kelvin rating, even if both lights have the same number of Lumens.
  • However, it’s important to note that Lumens and Kelvin measure different aspects of light, and they should not be used interchangeably. A high number of Lumens does not necessarily mean a high Kelvin rating, and vice versa.

How Can I Convert Watts To Lumens?

Watts and Lumens measure different aspects of a light source, with Watts measuring the amount of energy consumed and Lumens measuring the amount of light produced. However, it is possible to estimate the number of Lumens produced by a light source based on its Wattage using the following steps:

  1. Look up the efficacy rating of the light source in Lumens per Watt (lm/W). This information can usually be found on the packaging or product specifications.
  2. Multiply the Wattage of the light source by its efficacy rating in lm/W to calculate the number of Lumens produced.

For example, if a 60-Watt incandescent light bulb has an efficacy rating of 15 lm/W, the estimated number of Lumens produced would be:

60 Watts x 15 lm/W = 900 Lumens

It’s important to note that this method provides an estimate and the actual number of Lumens produced may vary based on factors such as the quality and age of the light source. Additionally, this method only works for comparing light sources with the same type of technology, such as incandescent or LED bulbs.

How Do I Choose The Best Bulb?

Choosing the best bulb for your needs can depend on several factors, including the brightness, color temperature, and energy efficiency you’re looking for. Here are some steps you can follow to choose the best bulb:

  1. Determine The Brightness You Need: Lumens are a good measure of a bulb’s brightness. Consider the size of the room, the height of the ceiling, and the desired level of illumination to determine how many Lumens you need.
  2. Consider The Color Temperature: Color temperature is measured in Kelvin and describes the color appearance of the light emitted by the bulb. Bulbs with lower Kelvin ratings appear warmer and more yellow, while bulbs with higher Kelvin ratings appear cooler and more blue. Consider the atmosphere you want to create in your space when choosing a color temperature.
  3. Choose The Right Bulb Type: Different bulb types have different energy efficiencies, color temperatures, and lifetimes. LED bulbs tend to be the most energy-efficient, with longer lifetimes and a wide range of color temperatures available. CFL bulbs are also energy-efficient but may have a slower start-up time and can contain mercury.
  1. Check The Bulb’s Label: Make sure to check the bulb’s packaging or label to ensure it is the correct shape and size for your fixture. Look for the Lumens, color temperature, and energy efficiency rating to help you make your decision.
  2. Consider The Bulb’s Dimmability: If you plan to use the bulb with a dimmer switch, make sure to choose a bulb that is labeled as “dimmable.”

By considering these factors, you can choose the best bulb for your needs, whether it’s for ambient lighting, task lighting, or accent lighting.


Lumens and Kelvin are two important measures that are used to describe the properties of light. Lumens are a measure of the amount of light emitted by a source and are commonly used to describe the brightness of a light bulb or other lighting fixture. The higher the lumen rating, the brighter the light output.

On the other hand, Kelvin is a measure of the color temperature of a light source, and is used to describe the perceived “warmth” or “coolness” of a light. Lower Kelvin values (2700-3000K) give off a warmer, yellowish light, while higher Kelvin values (5000-6500K) produce a cooler, bluish light.

Understanding the relationship between lumens and Kelvin can help you choose the right lighting for your space, based on your specific needs and preferences. A higher lumen rating may be preferred for task lighting, while a lower Kelvin value may be preferred for creating a cozy atmosphere.

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