When comparing light bulbs, you’ll likely see a specification called “CRI,” followed by a number. Most people do not know that this is a measurement of a light bulb’s color rendering index, and many of those who understand what the acronym is short for do not understand what that actually means.

A light bulb’s CRI measures the effect a light source has on the perceived color of objects and surfaces. High CRI lights makes virtually all colors look natural and vibrant. Low CRI causes colors to appear washed out, less saturated, or even to take on a completely different hue.

Compare the picture below. On the left, a high CRI light bulb is used to display colored pencils in vibrant, true color. On the right, a low CRI light bulb displays the same colored pencils, but the effect on their displayed colors is immediately noticeable. The low CRI light bulb displays the colored pencils with duller colors, producing less contrast and vibrancy in the picture.

CRI

It’s important to keep in mind that both the lights used in the example above have the same color temperature, meaning the color of the light they produce is the same. When comparing the CRI of any two light bulbs, it’s imperative that the color temperature of each are the same, or else the measurement is not comparable.

The closer a bulb’s CRI is to 100, the less shift in color is produced. The CRI scale is based off natural daylight, which has a color temperature of roughly 5000 to 6000K. This is the ideal range of color temperatures when using CRI. Color temperatures that are too low (common in conventional incandescent lighting) produce light that is very yellow, while color temperatures that are too high will produce light that is very blue.

Choosing your lighting source for your home or business is very important. Knowing what a bulb’s CRI rating is great, but knowing what that means is crucial. When armed with this knowledge, you can to make the right choices today, and experience true color for each day to come.