If you’re unsure what light bulb colors are all about, you’re not alone. Many light bulbs have a bunch of numbers on them and sometimes it’s hard to tell what they mean. Light bulb colors are measured by Kelvin temperature so you will see a number on a bulb like “2700K”, or “27K”, or even just “27”. Sometimes the number is included with a color rendering number which is a combination of “700”, “800”, or “900” series with the 27, so you will see something like “827” This photo shows how that particular number is represented:
As you can see, there is a part number LA19/12/827/OD-33. The color portion is the “27” or “2700K”, which is a warm color on the Kelvin scale. The 800 series number represents the color rendering, which is a scale indicating how accurate the light source is at “rendering” color. The higher the number, the more accurate the light color is. If the bulb had “841” stamped on it, then it would be an 800 series and “41” or “4100K” which is a cool (more white) color on the Kelvin scale. The higher the number of the Kelvin temperature, the “cooler” or “whiter” the color is until the really high numbers like 6000K which start to give off a bluish hue.
As a result of lighting output requirements by the government, you probably won’t see the “700” series numbers on newer LED bulbs because the “800” and “900” series rendering are now the standard. To make it simpler, just look for the number after the “8” or “9” which tells you the color.
Here is a chart showing light bulb colors with names and descriptions. The popular “4000K” also known as “cool white” is not shown at the top. Obviously, the 4000K is a color in between what this chart is representing as “Soft White” and “Daylight”.
Just to give you another example of a color number, here is one that is shown on the bulb box. As you can see, this one is a “4000K” color, which is a “cooler”, or more white on the scale. Some people prefer to use these in their fixtures because the light seems brighter and more “clear”. This is just a preference and the Kelvin temperature does not indicate how bright a bulb would be. For brightness, you need to look for “Lumens”, and that explanation is for another page.
For a more in-depth explanation of Kelvin temperature, please visit my page: Understanding Kelvin Temperature or “The Color of Lighting”.
Please feel free to leave any comments or questions below.