What Are LED Color Temperatures (Kelvins)

Heather Clouse
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What is Color Temperature (Kelvins)?

When most people think about color temperature, they visualize the colors of a campfire, small flames, or of an infrared heat lamp. All these objects create light with a color temperature.

Since they do not have the concept of color temperatures when talking about LED lights, many people have a hard time understanding how to pick LED bulbs that will fit their needs.

Yes, you can choose light color by picking a bulb with a certain color temperature or by using a color meter. **Typically when considering LED bulbs, think of a color temperature of 2700K or above. It is the most popular option used for residential lighting**.

Brief History of the Kelvin Color Temperature Scale

In the year 1848, a German physicist named Gustav Kirchoff created a law to help him better understand the current passing through different materials. You can guess what that law is called “Kirchoff’s Law of Thermal Colors.”

Anyway, his law states that the amount of energy of waves of different colors determines what we see as a certain color. Waves with only a little energy (blue) are cool, while waves that have more energy (red) are warm.

His law, along with advances in the study of spectroscopy, led to the creation of the Kelvin scale. Andrew A. Benson created a chart to help scientists and engineers easily convert scientific notation to whole numbers.

So, it’s the same as saying that when one color has a higher temperature, it has a higher color temperature as well.

For example, a color that has a temperature of 6,500K is as white as a color with a temperature of 5,000K.

Different Colors – Cool Or Warm Colors?

Using colored LED bulbs is a great way to create a unique atmosphere and mood for any indoor environment. The LED color temperature is a measure of how warm or cool a light source appears to the human eye.

The color temperature of a Kelvin color scale is a measure of what is commonly referred to as the color of light. Shorter wavelengths are more energetic and appear more blue. The longer wavelengths are less energetic and appear more red.

Typically, the lower the Kelvin (K) number, the warmer the color will appear. A lower K will have you consider the light close to the warmth of an incandescent bulb. The higher the K number, the cooler the color appears.

What Color Temperature Is Best For Specific Areas/Applications?

The color of light, whether that is sunlight, an incandescent bulb, or a LED, is measured in Kelvins (K).

At one end of the spectrum is blue light at around ~5000K, and at the other end is red light at ~2700K.

Most LED light bulbs, like the ones used for a growing applications fall between 2700K and 6000K.

Blue light is known to be the best blue light for plants but many growers have moved from traditional blue/white light to red/blue mix. These mixes are called red/blue actinic LEDs and have the best of both worlds.

The magic of this technique is that it stimulates the plant growth more effectively than either white or blue light alone.

As the graph shows, it grows a plant quicker than white or blue alone, but does not burn the plant or cause any damage. The red/blue mixes also encourage flowering.

The edge on light is a combination of blue and red. This is great for tropical and exotics species of plants as their lighting requirements are a bit different and they don’t like direct sunlight, which is too yellow.

The edge on lighting encourages fruiting and flowering in plants, which is why it is called “edge on”.

5000 to 6000/7000K – Daylight to Cool Daylight

The color temperature in Kelvin is often used when talking about types of light and is used to describe the light’s warmth or coolness (blue or red appearance).

The higher the number Kelvin is, the cooler the look of the light is and the lower the Kelvin number, the warmer the color.

5000K to 6000K: These are ideal for lighting freshwater aquariums and are cool white (blue) in color. Some report that the blue color may not be suitable for coral growth as the light appears to be slightly more stimulating to them than with lower color temperatures.

7000K: Also referred to as cool white, this color temperature is by far the most popular color for freshwater planted aquarium usage. With a color temperature that is bright white in appearance, these LED lights are an excellent choice.

8000K: The color temperature of the sun, many people like to use these to light up an aquarium. They are designed for freshwater and saltwater aquariums. However, it has been reported by many that this color temperature gives the ability to maintain corals.

3000 to 4000K – Warm White to Cool White

Warm white LEDs have more red and yellow in its color compared to the cool white LEDs.

These are typically used for household lighting and have a rating of “2700 to 3500K”. Many car and motorcycle tail lights are also built using warm white LEDs.

Cool white LEDs come with a blue tint and are typically used in outdoor use where red or yellow tint looks out of place.

Most common are outdoor white LEDs with a rating of “3000K”. Automobiles headlights often (but not always) employ cool white LEDs as they feel more natural and easily blend in on the road compared to warmer LEDs.

1800 to 3000K – Warm to Warm White

Warm and warm white are the most common color temperatures you will come across. The most common warm white LEDs have a color temperature of 3000K, which is the same as the warm white color of an incandescent bulb.

These common LEDs are great for general lighting. They give off a comfortable white light that is pleasing to the eye.

Consider Mixing and Matching

Most people really don’t understand or appreciate the different hues of colors available to them.

It’s the same with LEDs. If you were to place a set of white LEDs with a set of red LEDs, you’d be amazed at how different they look. All the extra color control settings you have with LEDs (dimming, color temperature, etc.) should be harnessed for different effects and moods. The right combination can be the difference between awesome and awful.

Take the orangey yellow that many of us love for our kitchen lighting. It’s produced by a combination of red and yellow phosphors with a hint of blue. We can also get that feeling from red LEDs, but the red for our kitchen would be more of the reddish pinky/purple family. These colors mixed together give us more light and are typically used in restaurants. Finding these combinations for particular applications is one of the benefits of having so much control over light color with LEDs.

How To Identify The Color Temperature of Lighting You Are Buying

When you are shopping for kitchen lights, for instance, it is normal to see different color temperatures mentioned in their specifications.

The light source’s color temperature influences the colors you see in the room. Lower color temperatures create a more comfortable light and look great with warm color tones while higher color temperatures make light that is more natural and easy on your eyes and look great with cool color schemes.

When buying LED lights it’s best to choose a lamp that has a color temperature range from 3000K (warm white) to 5000K (cool white).