An equal light temperature does not automatically mean that the light is perceived the same. The colour rendering of a lamp depends on the composition of the light, that is, the colours that make up the light.
To measure how true to life a lamp displays colours, we use the Color Rendering Index (CRI), also called the Ra value.
CRI 100 (100%): all colours are displayed optimally, as close as possible to natural light.
Lower than 100: colours appear less vivid or unnatural.
A higher CRI is especially important in spaces where colour recognition is crucial, such as in the kitchen, when applying make-up, in studios or shops.
Average CRI values per lamp type
| Lamp type | Colour temperature | CRI |
|---|---|---|
| Incandescent bulb | 2600 K | 95–100 |
| Halogen | 2800–2900 K | 95–100 |
| Compact fluorescent lamp (CFL) | 2700–6500 K | 80 |
| LED lamp | 2100–6500 K | 80–90 |
Note: The exact CRI value can vary depending on the brand and type of lamp. Always check this on the packaging or specifications of the lamp.
Eye sensitivity and personal colour perception
Everyone experiences light differently. This is called eye sensitivity, the way the human eye perceives colours.
Our eyes contain three types of light-sensitive cells (cones), which are mainly active in the yellow part of the spectrum. In this area, our visual acuity is highest, but this varies per person.
Because of these differences, a lamp with the same CRI or colour temperature may be perceived as warmer or cooler by one person than by another.
Tip: Test lamps in a shop or showroom to discover which type of light best suits your preference and space.
Why CRI is important
A higher CRI ensures more naturally appearing colours.
CRI affects ambience and productivity: warm light with a high CRI relaxes, while cool light with a high CRI can enhance concentration.
In work environments, shops and creative spaces, a CRI of 90 or higher is recommended.