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What is CRI? Color Rendering Index Explained

What is CRI? Color Rendering Index Explained

Color Rendering Index (CRI)

Are you looking for new lighting for your family room or kitchen? Perhaps you want to spruce up your lawn for nighttime use? Regardless of what type of lighting you're looking for, you'll probably want to understand which CRI you need. Use this guide to answer the question you're inevitably asking: "what is CRI?"

What Does Color Rendering Index Mean?

Light sources work using specific light spectrums, which is why colors appear very bright in some lights but dull in others. Lamps, overhead lighting, and illuminated devices are measured according to the Color Rendering Index. The closer a lighting source is to natural daylight, the better, as this shows colors more precisely. CRI is determined using a scale of 0 to 100.

What Is the CRI Lighting Scale?

The CRI lighting scale typically has three different categories: CRI up to 70, CRI between 70 and 90, and CRI between 90 and 100. Lighting sources with a CRI under 70 alter how you see colors and typically include fluorescent tubes, low-pressure sodium vapor luminaries, and mercury-based clear luminaries.

Lighting that has a CRI of 70 to 90 displays colors nearly true to their form, but isn't as precise as lighting with a CRI of 90 to 100. Satisfactory lighting includes standard LED lights, many metal halide luminaries, and high-pressure sodium vapor luminaries. If you want the best lighting with the most precise coloring, aim for a CRI of at least 90. Think high-fidelity LED lamps and basic incandescent lamps.

Why Is CRI Important in LED Lighting?

Understanding how CRI works and its relation to LED lighting is essential to ensure you choose the right type of lighting for your project. For example, highway lighting systems don't need a high CRI because drivers focus on the words on signs or the lines on the road, not the colors of the items being illuminated. On the other hand, a boutique that sells clothing should have overhead LED lighting with a CRI of at least 80, because shoppers rely on accurate color representation when choosing clothing and accessories. 

How Do You Find CRI?

Testing a lighting source's CRI requires the use of several precise color patches. Using a spectrophotometer, you can measure the color of the light reflected off the patches under various light sources. The difference between the measured color and the real color creates a score. The larger the difference, the more the color perception is off, and the lower the lighting source's CRI is. A standard test uses eight colors.

Lighting is a fun way to spruce up your home, show off your business products, or even make an eye-catching art piece. Work with a professional to help you find the best CRI light source for your needs.