How To: All About Lighting Temperature

Colour temperature — measured in Kelvin — is the difference between a kitchen that feels alert and one that feels warm, and between a bedroom that helps you sleep and one that wakes you up. It's also the spec on a lightbulb that most people ignore. This guide explains what the numbers mean and how to choose.

What is colour temperature?

Colour temperature describes the hue of light a bulb produces, measured in degrees Kelvin (K). Lower numbers — around 2700K — are warm and yellow, like candlelight. Higher numbers — 5000K and above — are cool and bluish, like overcast daylight. The middle ground, around 3000K to 4000K, sits between the two.

The counterintuitive part: higher Kelvin means cooler-looking light. The number describes the temperature a theoretical black-body radiator would have to be heated to in order to glow that colour, which is why a "warmer" 2700K bulb actually has a lower number than a "cooler" 5000K one.

What do common Kelvin values look like?

2700K is the warm yellow-orange of an incandescent bulb or candle — cozy, intimate, slightly atmospheric. 3000K is similar but cleaner, often described as "warm white." 4000K is neutral, close to mid-day daylight. 5000K reads as bright, crisp white. 6500K is the cool blueish white of a clear-sky afternoon — alerting, but cold in a residential setting.

Manufacturers' definitions of these temperatures vary slightly, so two bulbs both labelled 3000K may not match. This is one of the more common sources of mismatched lighting in a finished space.

Which colour temperature should I use in each room?

Match the temperature to how the room is used. Bedrooms and living rooms — places to relax — benefit from warmer light around 2700K to 3000K. Studies have linked warmer light in the evening to better sleep quality. Kitchens, bathrooms, and home offices — where you need to see clearly — work better at 3000K to 4000K. For art collections, walk-in closets, or any room where colour accuracy matters, true white in the 4000K to 5000K range gives the most honest read.

The lighting designer Christian Lo of Anony, whose fixtures we carry, frames it as a question of how the room is lived in: "If you actually work at your dining table, we'll want to cool that colour a bit." Function determines temperature more reliably than aesthetics.

Function determines temperature more reliably than aesthetics. Match the Kelvin to how the room is used, not to how the fixture looks.

What temperature works in commercial spaces?

The defaults break down in commercial work. An art gallery needs colour-accurate light close to 4000K so paintings render the way they would outside the space. A jewellery shop benefits from cooler light to make stones sparkle. A butcher wants warmer red tones that flatter meat. A restaurant changes through the day — a café might run cooler in the morning to feel fresh and warmer in the evening to feel inviting.

For commercial fixtures with adjustable colour temperature, the same fixture can do both. Otherwise, choose for the dominant use of the space.

Why does the same Kelvin number look different from different brands?

LED quality varies, and "3000K" is a target rather than a guarantee. Cheap LEDs often skew green or pink at the same nominal temperature, and the colour can shift over the bulb's life. The best lighting brands quality-test bulbs before shipping them with their fixtures — Anony, for example, sources from ten to twenty manufacturers and only ships the ones that match their colour reference.

For any fixture you care about, buy the bulbs from the same supplier as the fixture if possible, or from a dedicated lighting supplier rather than a general retailer. The price difference between a good LED and a poor one is small. The visual difference is not.

Browse fixtures and recommended bulbs in the lighting collection.