Colour temperature describes how warm or cool the light of a source appears, expressed in kelvin (K). The lower the value, the yellower and warmer the light; the higher the value, the whiter and bluer. It is about the colour of the light, not the amount of light (that is luminous flux, in lumens) and not the consumption (watts).
The scale confuses people who have not met it before: “warm light” has a low kelvin value.
| Colour temperature | Description | Where it fits |
|---|---|---|
| About 2700 K | Warm white | Living room, bedroom, restaurant |
| About 3000 K | Warm white / soft white | Kitchen, bathroom, hallway |
| About 4000 K | Neutral white | Workroom, garage, office |
| About 5000-6500 K | Cool white / daylight | Workshop, plant room, inspection work |
Where it is used
- Living spaces — 2700 K matches the light of the old incandescent lamp and gives a calm, comfortable feel
- Work and hobby spaces — 4000 K gives a neutral picture in which colours can be judged and you stay more alert
- External lighting — warm light (2700 K or lower) is less disruptive to insects and bats than cool, blue-rich light
- Tunable lighting — many LED fittings now let you switch colour temperature by control or app
Practical tips
- Keep it consistent per room — different colour temperatures side by side look restless and make both lamps look wrong
- Look at the colour rendering index (CRI/Ra) too — it tells you how faithfully colours appear under the lamp. For living spaces Ra 80 is the minimum, Ra 90 or above is clearly better
- Limit cool light in the evening — blue-rich light late in the evening is stimulating; use warm white in the living room
- Check when replacing — when buying a single replacement LED, match the kelvin value printed on the packaging to the existing lamps
Related terms
- LED lighting
- Daylight factor
- Recessed spotlight
- Indoor climate
- Earth colours
- Light transmission
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