What is Light Bulb Color Temperature and How it is Measured?

Knowledge about your household technologies can never be wasted or redundant. The more you know about how things function, the better choices you can make and the fewer headaches you will have once you will be using the particular technology on everyday basis.

Lighting is no exception and this time you will be introduced to something which is known as a light bulb color temperature. When deciding on purchasing the appropriate light bulbs we tend to think about such aspects as price, energy efficiency, material, fixture, design etc. Undoubtedly all these are very important factors to consider and they surely have to be thoroughly looked upon but rarely we talk about the light itself and even less – about its colors and desired effect the light is supposed to have on our room and space.

Hence this article will explain you why it is important to know about light bulb color temperatures. It will be your basic guide through the spectrum of light bulb color temperatures and alongside will provide some practical tips on when the color temperature should be considered and what sort of situations matches various colors.

What is light bulb color temperature?

The very notion of “bulb color temperature” is very brief and straightforward.

Although majority of lamps are produced to emit so called “white light”, the varieties of this light significantly differ from each other and can provide different colors such as “warm white” or “cool white”. In other words, different type of light produced by different light bulbs is what we understand with “light bulb color temperature”.

Seems that it is not much of a big deal but as reading further on to the next sections of the article, you will see that light bulb color temperature DOES matter and it should not be underrated if you really want to enjoy proper lighting and set up the right ambience, mood and appearance for different spaces (home, workspace etc.).

Color temperature difference on object. Source - http://facweb.cs.depaul.edu

Color temperature difference on object. Source – http://facweb.cs.depaul.edu

How light bulb color temperature is measured?

Color temperature is measured in Kelvin degrees and they are typically denoted by a numerical figure followed by the letter “K”. You might become a bit confused when trying to understand the Kelvin scale since it works opposite to Celsius and Fahrenheit scales. In Kelvin scale lower values actually equate to warmer colors and vice versa.

The beginnings of measuring the hue of “white” can be traced back to the late 1800s and are associated with the achievements of a notable British physicist named William Kelvin who was the first one to manage to heat a block of carbon and made the notes of the changes in its color. The block of carbon naturally changed its color switching from dim red, then on to various shades of yellow and eventually reaching bright bluish white at the highest temperature. This discovery triggered the whole idea of different color temperatures of light. Further on, as the artificial lighting was introduced in our households and workspaces, plus it evolved to different bulb types apart from “conventional” incandescent bulbs such as LED and CFLs, the color temperature became considered as another significant feature of a lamp. This enabled manufacturers to produce lamps that have different color temperatures and hence now the choice is as wide as ever.

The scale given below applies to some of the most common temperatures used in modern lighting applications. Nevertheless keep in mind that some bulbs (e.g. incandescent lamps) are tied to a specific color temperature simply due to their working principles. On the other hand, such technologies as LED are more flexible and can provide numerous color temperatures.

  • 2700K – Extra Warm White/Warm White. Similar light as produced by incandescent bulbs. Provides warm and cozy feel.
  • 3000K – Warm White. This is the color which is produced by majority of halogen lamps.
  • 3500K– White. Standard color of majority of CFL lamps.
  • 4000K – Cool White. Provides sort of high-tech feel.
  • 6000K – Daylight. Found in CFL lamps, emulates natural daylight.
  • 6500K – Cool Daylight.
Color temperature chart. Source - http://lowel.tiffen.com

Color temperature chart. Source – http://lowel.tiffen.com

When light bulb color temperature should be considered?

Now that you know a bit more about what light bulb color temperature is, you probably wonder “Now, what am I supposed to do with this information?” Let’s reveal some of the situations when you should consider opting for not only appropriate bulb type but also seeking a color temperature that would be relevant to the specifics of your home and office design.

  • Impact on your mood. Some people are very sensitive once it comes to different lights and, in fact, many people claim that the temperature of color of the light they receive throughout the day impacts their mood significantly. Actually even some scientific studies seem to agree that, for instance, by using a light in the blue portions of the spectrum it is easier to wake up in the morning.
  • Lighting for your home. Typically home is a place where you relax and do not have to think about work, so in your home you probably want to have a cozy and warm feeling. This can be done by using lights of around 2700K– warm white. This light is known to be comfortable for home circumstances.
  • Lighting for your bathroom. This might be very relevant to our female readers. Let’s say you want to do your daily make-up but somehow looking at your bathroom mirror does not help to do everything right, because the light is too dark. That’s one of the reasons daylight bulbs are becoming more and more popular and are widely used to illuminate bathroom space making it easier for women to see how their make-up will look like once they go outdoors.
  • Lighting for your workspace. Workplace, on the other hand, is completely different case. For a lot of people work is related to reading and using computer and such tasks undoubtedly requires proper lighting as well. It is suggested that you equip your working space with bulbs that have light color temperature of around 3500K. This is also known as “cool white”. It is mainly used in fluorescent and LED lights and is known to have positive effects on environments where you need to read or perform detail-oriented tasks.


Blogger, editor, developer who loves green living. Interested in photovoltaics and solar lighting. Reviewing solar products since 2013.

You may also like...

3 Responses

  1. Bob vickroy says:

    What would be an inexpensive device to measure color temperature of lights in a room that would also cover the blue temperatures?

  2. Emma Wilson says:

    Excellent guide. Lighting plays a big role in home decor and it’s important to consider which temperature to use for every room. Thanks for the valuable tips!

Leave a Reply

Your email address will not be published. Required fields are marked *