Color Rendering Index – CRI Simply Explained

Color Rendering Index, or CRI, is a metric that assesses the extent to which a light source replicates colors in comparison to natural light. On a scale from 0 to 100, a higher score indicates greater similarity to natural light. CRI is an important consideration when selecting indoor lighting, as it directly affects color appearance within a given space.

A light source’s CRI score influences its lighting performance in indoor settings. Higher scores generally indicate superior color replication, which is especially critical in environments that rely heavily on color accuracy, such as art galleries, retail stores, and medical facilities. Conversely, locations such as warehouses and parking garages that do not necessitate precise color replication may not require a high CRI rating.

Nevertheless, it’s crucial to recognize that a high CRI score alone does not guarantee the light source’s suitability for all indoor settings. Other factors like light output, color temperature, and energy efficiency must also be taken into account when selecting indoor lighting.

Before and After shot showing a low CRI (High Pressure Sodium around 24 CRI) compared to 1st Source Lighting’s LED replacement (Samsung LED’s at 82+ CRI)

Emitted light spectrum determines the CRI of the lamp. An incandescent lamp (middle image) has a continuous spectrum and therefore a higher CRI than a fluorescent lamp (lower image). The top image shows the setup of the demonstration from above. Source – Wikipedia

CRI is determined by comparing how accurately a light source renders eight specific colors with their appearance under natural light. These colors include red, yellow, green, blue, purple, pink, orange, and white. Each color’s accuracy score is assigned a value between 0 and 100, with the final CRI score representing an average of the eight values.

In general, a CRI score of 80 or higher is deemed good, while 90 or higher is considered excellent. It’s essential to keep in mind, however, that a high CRI score is not always indicative of the light source’s appropriateness for a specific indoor setting.

For instance, a high-CRI light source with a color temperature that is too warm may result in a yellow or orange tint, which may not be desirable in some circumstances. Similarly, a high-CRI light source with insufficient light output may not provide enough illumination for a given space.

Low CRI (Left) vs High CRI (Right)

When selecting indoor lighting, it’s critical to consider the specific needs of the space in question. In environments that necessitate precise color replication, such as art galleries, museums, and medical facilities, lighting with a CRI score of 90 or higher may be necessary.

In contrast, in locations where accurate color replication is less crucial, such as warehouses or parking garages, energy efficiency and light output may take precedence over CRI scores.