Two identical rooms, identical fittings, one difference: the bulb in one is 2700K and the other is 6500K. The first feels like a home. The second feels like a dentist's waiting room. Colour temperature is the highest-impact lighting decision most people never consciously make.
What do the kelvin numbers mean?
Colour temperature is measured in kelvin (K). Lower numbers are warmer and more orange, like candlelight and incandescent bulbs. Higher numbers are cooler and bluer, like overcast daylight. It has nothing to do with brightness — that's lumens, a separate spec on the box.
| Kelvin | Called | Looks like |
|---|---|---|
| 2200–2700K | Extra warm / warm white | Candlelight, old incandescent globes |
| 3000K | Warm white | Halogen; warm but crisp |
| 4000K | Cool white / neutral | Office lighting |
| 5000–6500K | Daylight | Overcast midday sky |
Which colour temperature for which room?
Bedrooms, living rooms, dining, hallways: 2700K. These are rooms for winding down, and warm light is what your body reads as evening. This is what we fit across our indoor wall light range, because a wall light's whole job is atmosphere.
Kitchens: 3000K, or 4000K over work surfaces only. You need to see what you're chopping. Task areas take cooler light; if the kitchen opens onto living space, keep the overall tone at 3000K so it doesn't clash.
Home office: 4000K while you work. Cooler light genuinely helps alertness. Put it on its own switch so the room can go warm after hours.
Outdoors: 2700–3000K. Warm light flatters brick and render, feels welcoming at a front door, and attracts fewer insects than cool white.
Where does cool white always fail?
Anywhere you relax, and anywhere near stone. Cool white in a bedroom or lounge reads as institutional. And through translucent materials it's actively destructive: alabaster's amber glow comes from warm light scattering through the stone — put a 6500K bulb behind it and you've turned a $400 stone fitting into a fluorescent panel. Same for linen and ceramic diffusers. If you buy nothing else from this article: never put daylight bulbs in a decorative wall light.
Can you mix colour temperatures in one house?
Yes, and you should — by function, not at random. The rule that keeps it coherent: consistent within a sightline. Any lights you can see at the same time from where you're standing should match. A 4000K kitchen bench light visible from a 2700K lounge is the clash people can't name but always feel.
Frequently asked questions
Is warm white or cool white better for a living room?
Warm white, 2700K. Living rooms are for relaxing, and warm light is what makes them feel that way in the evening.
What is the best colour temperature for a bedroom?
2700K, dimmable if possible. Some people go to 2200K for bedside lights used right before sleep.
Do warm white bulbs use more power?
No. Colour temperature and energy use are unrelated in LEDs — a 2700K and a 6500K LED of the same wattage cost the same to run.
What does 4000K look like?
Neutral-to-cool white, like a modern office. Good for task areas, harsh for living spaces.
