Infographic Lumen Light Spectrum

Did you ever switch to a light source with a higher level of watts because you wanted more brightness in the room? If yes, then there is no need to worry. We all have probably done this at some point in our lives. Back in the day, a light bulb with a higher value of watts written on the label used to give a higher level of brightness. 

But modern and advanced lighting technology has forced us to understand our lights in a more detailed manner. The modern and newer form of technology used in lights like LED technology has changed everything. 

The level of brightness of light used to be roughly similar to the watts consumed by a light source. However, modern technology has made it possible to attain more illumination in a space with the help of a light consuming low voltage. This change in technology has made it essential to understand that watts are not the measure of a light’s brightness. 

This new information makes us wonder, if a higher-watt light doesn’t mean a brighter version of the light than what does? The answer to this question is Lumens. Lumen is the unit that helps us measure the brightness of a light.

What is a Lumen? 

Lumen is the only correct way to calculate the total amount of light visible to a naked human eye. Every light brightens up a room differently. Some lights are white in tone, and others have a yellow touch to them. Some lights are bright in nature, while others are dim. There is also a black light that is not at all visible to a naked human eye. 

Various factors impact this, but watts certainly has nothing to do with the brightness or the color of light. This comparison between the intensity of light and its watts has been nothing more than a myth. To understand this, let’s have a look at the difference between Watts and Lumen.

Difference between Watts and Lumen?

If we want to clear this myth about watts being the unit of brightness, we have to understand the difference between watts, which is a unit of power consumption, and lumen, which is the correct unit for measuring the brightness of a light. Let’s look at the differences between lumens and watts to understand this.


A measure of electricity consumed by an electrical device, a watt refers to the actual units of electricity consumed in the process of using a gadget. A watt doesn’t have any relation to how bright a light is, even though it is sometimes believed otherwise. 


The actual unit to denote the brightness of a light, lumen refers to the visible intensity of light. 

From this evaluation, we can conclude that watts are not the measure of a light’s brightness. They are the units to measure how much power a gadget consumes. A device which is consuming more wattage doesn’t necessarily give out a brighter light. Lumens are the only correct units to denote the intensity of light. After we have understood this, the next thing to understand is the difference between a Kelvin and a lumen. 

Kelvin is essentially the temperature of the light. Discussing Kelvin in relation to lumens is essential because the heat of the light gives a glow that results in different shades of lights. This glow which heating gives off is often the reason why we mistake lumens with watts.

Let’s consider this. When you continuously heat a metal, it starts glowing. It begins with bluer shades and gets more yellow as it becomes hotter. The same principle also implies the different shades of light emitted because of the temperature.

What is Kelvin?

Like Celsius and Fahrenheit, Kelvin is also a symbol used to denote temperature. The relationship between the volume and temperature of the gas inspires the advent of Kelvin. Named after Sir Kelvin, Kelvin can compare with a degree. 

It is precisely equal to a degree. For denoting Kelvin, scientists use a K without the degree symbol in a degree unit. It is worth noting that there are no negative integers defined in Kelvin.

Light Color Temperature

The temperature of light can be measured on the Kelvin scale from 2700K for incandescent bulbs to 7000K for LEDs. Even the different forms of lighting solutions have their temperature ranges based on the design, wattage, and efficiency. 

It would be best if you kept the purpose of your lights in your mind. The use of the light helps you decide the type of temperature scale that the lighting should have.

Light temperature impacts the shade of yellow or blue in a light. Cooler lights will have a blue hue, while a warm light will have a yellow tone. One needs to choose a warm temperature light for the lighting of places to relax in, such as living rooms and bedrooms. It is better to use cool temperature lights in working areas like the office or a study room. 

This cold temperature of the light is why one sees yellow lights in bedrooms or sitting areas, and blue lights in workplaces. It becomes imperative that thought is given to the temperature of light while choosing the lighting of the room.

Here is how the warmth of light impacts us:


This is the light that is closer to the yellow end of the spectrum, offering a warm and comfortable glow that helps generate a feeling of comfort and relaxation. These shades of lighting are great for accent lighting, as they help develop a soothing ambience. 

Most incandescent bulbs offer lighting in this temperature range. But this lighting is not useful for doing work, as it is dimmer and may negatively affect vision. The negative impact of this light is the reason why warm lights are better for bedrooms and lounges.


This range of lighting is closer to the higher end of the spectrum and is white or bluish-white in hue. This shade of light is better for working in as it is closer to daylight and helps mimic it better. The brightness helps us to focus and have better visibility. This level of intensity makes the cooler lights preferred for offices, classrooms, meeting rooms, and study rooms. 

Below are some of the temperature ranges with their color shade and their uses for different lighting purposes:

Below 2000K Range 

The light bulbs with temperature below 2000K will give off a dim yellow glow similar to that of candlelight. This light will also feel warm. These types of light are ideal for settings where soothing and ambient lighting is required. 

2000K to 3000K Range 

Even though the range of 2000K to 3000K temperature of lighting will give off a white light, it has a soft glow, which sometimes makes it look yellowish. These lights have utility in places where high brightness lights are not required, such as living rooms or outdoor areas for comfortable vision.

3000K to 4500K Range 

In this range of 3000K to 4500K, the bulbs give off a bright white light, which is best suited to areas where we need to get work done, such as office spaces, kitchens, and other areas that require high energy to support work-related activities.

4600K to 6500K Range

This range of 4600K to 6500K gives off a very bright light that most suits display areas and some work-related places where a very high level of brightness is needed.

6500K and Above Range

The brightest form of light is 6500K and above. This level of lighting is suitable for commercial places that need bright task lighting.

How to Relate Lumen and Kelvin?

A lumen measures how much light in the visible range is getting generated from any particular light source. When a light source has a larger lumen, it means that the light is brighter. All light bulbs, be it new-age LEDs or old-fashioned incandescent bulbs, use lumens to evaluate how much light is getting produced. LEDs are highly energy-efficient and can provide the highest amount of light output at lower wattages.

Where does a Lumen Fall Short in Meeting Our Expectations?

Before we can understand the shortcomings of a lumen, let us understand what makes white light. A spectrum of light is the display of all colors, which, when combined, makes white light. A spectrum of light is like the one seen in a rainbow. These components of white light appear to us in particular colors because they have a different wavelength. 

Let’s consider the color blue for a minute. The wavelength of a blue color lies between 380nm and 500nm. You know that there are different shades of blue. Some shades of blue are dark, while others are light. This is because of the difference in the wavelengths. A light tint of blue color leans towards 500nm, and the dark blue leans towards 380nm. These wavelengths help us determine the color of light.

Have you ever felt discomfort while staring at a dark red or blue light while yellow or green light feels a lot more comfortable? This variation in how our eyes see a color of light is because our eyes have different sensitivity towards different views. We are more comfortable with shades of yellow and green, while red and blue might be tough to see for the eye. 

Now that we have understood the difference between different colors of light, the next thing to note is how a white light becomes white. We already know that white light is a mixture of all colors. The lights manufacturers use different combinations of light colors to create white light in the LED lights that we use today. 

It is worth noting that different LED bulbs that emit different colors combine in a LED light. When we say that we combine different colors to make the white light, we refer to the different color LED bulbs in a LED light fixture. These different light bulbs are combined to make white light. The typical color combination used for this purpose is red and blue. More advanced versions of light use yellow and green lights to create white light.

We know that our eyes see yellow and green colors better than red and blue colors. The white light made with blue and red combination seems to be a bit dull when compared with the lights made of yellow and green.

Since lumen is the unit of how bright the light feels to our eyes, this is not the most optimum way of knowing how bright the light exactly is. While lumens are still very useful when it comes down to selecting the lights for your home, it is not very useful for other usages.

Other Things that Impact the Brightness of a Light

It is worth mentioning here that lumens are not the only thing that impacts the brightness of a light. When you are trying to get a brighter version of the light bulb installed in the house, the lumen is not the only thing that needs to be kept in mind. 

For example, let’s say you want to install light bulbs to brighten up your study table. Installing a light on the wall will only brighten your study table so much. A lot of lumens get lost because of the openness, hence reducing the efficiency of a light bulb. 

Suppose you want to light up a study table and use a 5-watt bulb which radiates 280 lumens in all directions. The specific purpose of that light bulb is to illuminate your study table and not the entire room. In such a scenario, it is better to use a lampshade to direct the lumens to one direction or use a light that flows in one direction only. By considering this, you can not only do with a light wattage bulb but also save some power consumption.

There are many other things called Light Loss Factors that come into play. Things like optics, voltage, ambient temperature lumen depreciation also impact the brightness of the light.

While it can seem daunting to consider all the factors, experimenting with different lights is the best way to determine which lights are best for your space.


Please enter your comment!
Please enter your name here