Many Shades of White: Warm vs Cool LED Christmas Lights

You remember learning about the color spectrum years ago in Physical Science 101? Do you also have a dim memory of some guy named “Kelvin”? Before you purchase or add to your Christmas light collection this season, you may want to refresh what you learned about color spectrum, Kelvin, and temperature. If you don’t, you may end up with white lights that are different shades of white and don’t match.

Don’t worry—we can clear it all up for you!

First, some science review…

Additive color mixing simulated.png
Additive color mixing simulated” by PkoOwn work. Licensed under Public domain via Wikimedia Commons.

Color is dependent on the frequency of light waves. (This better not get too technical…)

When you see colors as light, your brain is really interpreting wavelengths in the visible light spectrum. (It’s easier for my brain to perceive light than understand it.)

Different colors have different wavelengths. (Ok, that part isn’t so hard.)

Combining colors of light can result in multiple wavelengths. (Say what??)

White light has many wavelengths in it, because it combines all the colors. (Wow! White is something special!)

Science Fact Number 1:

White light is obtained by combining all frequencies of visible light.

However, you can also get white light if you just add red, green and blue light in equal intensities. The equation for this is no surprise:

R + G + B = W

Uneven intensities of these lights can be combined and you’d still get what’s recognized by the human eye as “white,” but these would be different shades or tints of white if you compared them side by side. (I get it… like the difference in white Christmas lights?)

Science Fact Number 2:

As temperature increases, light changes color. This is called “color temperature.” Color temperature is really the hue that the naked eye perceives the light to be. As temperature goes up, the light’s perceived color becomes whiter (cooler). While we’re used to Fahrenheit or Celsius for atmosphere and room temperature, light temperature is measured in kelvins. The higher the kelvins, the whiter (or cooler) the color of light will be.

A warmer light (lower kelvins) is perceived by the eye as more yellow. A cooler light (higher kelvins) gives off a white-bluish light.

There is range for different shades of white LEDs. Holiday LED’s white light range is:

  • 2800K to 3300K for a warm white light (2700K to 2900K for warm white retrofit bulbs)
  • 9500K to 10500K for a cool white light (8000K to 9500K for cool white retrofit bulbs)

There are 2 ways to get white light from LEDs:

  • Combine light from red, green and blue colored LEDs.
  • Use a blue LED with a phosphor coating. The coating emits a warmer yellow light when the blue light from the LED shines through it.

In 1995 the first white LED was developed using a YAG phosphor coating, to mix yellow light with blue, to produce a light that appeared white to the human eye. In fact it really had a yellowish green color. But since then, the technology has improved—and the consistency of warm white or cool white lights has too.

Purchasing White LED Christmas Lights

Selecting a standard white Christmas light used to be simple–there was only one choice: clear. With the introduction of LED Christmas lights, more choices became available, and it has become a bit more complicated. Now consumers can choose between warm white, cool white, champagne, and many variations in between. All of the new shades of white became possible, because LED technology allows the manufacturer of the LED to apply different phosphor combinations, to create a white light of different color temperatures.

(Do I have to understand light theory and color temperature to buy Christmas lights?)

You don’t have to understand light frequency, color addition, kelvins, and color temperature to buy lights, but you should understand that there are different types of white available.

Purchase only from a retailer who understands the difference and can help you select the correct “warm white” or “cool white” lights for your decorations. (Any suggestions on that?)

Buy from one manufacturer.

Often warm white lights can differ in tone between manufacturers and batches.

Try to buy from the same manufacturer when possible. The right one will be able to help match whites.

Know what look you are going for. It’s all a matter of personal preference.

Cool white LED Christmas lights produce a much cooler and vibrant white color. Previous versions of the cool white LED were almost blue looking, while newer versions of the cool white LED are more of an icy white and reflect very little blue hue. Cool white is really a fantastic color, and is used effectively for decorations that involve snow, ice, or crisp white tones. It also works wonderfully as an accent to color displays, as it picks up and enhances the brightness of colored sets.
Warm white LED Christmas lights are similar to the light given off by an incandescent bulb . The color of warm white in and LED has improved greatly over the past few years. Many people still associate white LED Christmas lights, with cool or blue looking lights. While there are some white colors of LED that reflect a bluish white color, there are now quality warm white sets available that mimic closely the warm, traditional, ambient color of standard incandescent lights. Warm white Christmas lights are a great selection for classic Christmas tree lighting and other traditional displays, where a warm, soft light is desired.

It’s just a matter of preference.

There are even some great combinations of warm or cool white with other colors:

When making your purchase for holiday LED lights, you should tell the retailer whether you want warm or cool LED lights. If you mention what kelvin range you’re interested in, they should be able to tell you if their LEDs are within that range.

At Holiday LEDs, we have warm white or cool white lights, for all your decorating needs. If you don’t want to be bothered with figuring out light spectrum, wavelength, color temperature, and kelvin, contact us for guidance on matching your white lights. (That sounds pretty easy. I like that!)