Use 2700K (very warm white) in living rooms, bedrooms, dining rooms and outdoors; 3000K (warm white) in kitchens, bathrooms and hallways; and reserve 4000K (neutral white) for pure task zones — a utility room, a garage bench, a desk lamp for close work. Keep one temperature per layer, never mixed within a room's main lighting.
Walk into a room that feels inexplicably cold and the culprit is almost never the sofa. It is usually a 4000K bulb doing its honest, clinical work in a space that wanted candlelight. Colour temperature — the number in kelvin on every bulb box — is the cheapest thing to change in a room and the most common thing to get wrong, because the box names it in words ("warm white", "cool white") that brands use inconsistently.
UK homes have a particular version of this problem. Our daylight is northern — grey and blue-cast for much of the year — which makes cool bulbs feel even cooler than they would in a catalogue photographed somewhere sunny. And our rooms are small by international standards, so one wrong bulb colours the entire space. This guide gives you the number for every room; the companion piece on how colour temperature actually works covers the science underneath.
The scale in one minute
Kelvin runs from the amber of a candle (about 1800K) through old-fashioned incandescent (2700K), to bright midday daylight (5500K and beyond). Lower is warmer, higher is colder — and, counter-intuitively, the number has nothing to do with brightness. A 2700K bulb and a 4000K bulb can be exactly as bright as each other; they just render the room in different moods. Brightness is measured in lumens, which we cover separately.
Room by room
| Room | Temperature | Why |
|---|---|---|
| Living room | 2700K | Relaxation space — very warm white flatters timber, brass, books and skin, and suits evening use |
| Bedroom | 2700K | Warm light in the evening supports natural wind-down; cool light before bed works against sleep |
| Dining room | 2700K | The closest electric light gets to candlelight — food and faces look their best |
| Kitchen | 3000K | Warmth with enough clarity for knife work; 2700K for any pendant over a table or island |
| Bathroom | 3000K | True-enough skin tone at the mirror without turning the room clinical |
| Hallway & stairs | 2700–3000K | Match whichever rooms it connects — the eye notices the change at a doorway |
| Home office | 3500–4000K | The one room where cooler light earns its keep: alertness for daytime work |
| Outdoors | 2700K | Warm light reads as welcome; cool floodlight reads as security fencing |
The living spaces: 2700K, without exception
Living room, bedroom, dining room. These are evening rooms, and 2700K — the colour of the incandescent bulbs every UK home ran on for a century — is what our eyes read as domestic warmth. Cool light flattens exactly the materials these rooms rely on: oak goes grey, cream walls go institutional, brass loses its glow. If a living room still feels cold at 2700K, the problem is usually a single bright ceiling source rather than the temperature — the fix is layering, which the fundamentals guide walks through.
The working rooms: 3000K
Kitchens and bathrooms need to flatter and function at once. 3000K is the compromise that a century of lighting design has settled on: warm enough that the room still belongs to the same house as the living room, crisp enough that chopping an onion or shaving is comfortable. Go warmer over social spots — an island pendant, a bath sconce — and never go cooler than 3000K in either room unless you genuinely want the dentist's-waiting-room effect.
The exception: the home office
Cooler light measurably supports alertness, which is why offices run at 4000K. If you work from home, a 3500–4000K desk lamp or downlight over the work zone earns its keep — but scope it to the desk, not the whole room, so the space can return to being a home at six o'clock. This is the strongest argument for buying one bulb family in several temperatures.
Can't decide? Switch it.
The Kaos ceiling light has a physical switch on the fitting that moves it between 2700K, 3000K and 4000K — so a hallway, landing or utility room can be tuned in place rather than committed to at the checkout.
The two rules that matter more than any number
Rule one: one temperature per layer. A row of downlights with one 4000K stray in it, or a three-arm pendant with mixed bulbs, always looks broken — even to people who could not tell you why. When you choose a room's temperature, replace every bulb in that layer to match it, and label the spares.
Rule two: temperature is not accuracy. Two 2700K bulbs can render the same room differently, because warmth and colour accuracy are separate specifications. Accuracy is CRI — and it is the difference between oak that looks like oak and oak that looks like laminate. Cheap warm bulbs are warm but muddy. Look for CRI 90 as a floor, CRI 97 where the room deserves it.
Nimbus Pro GU10 · CRI 97
The same bulb in 2700K, 3000K and 4000K, all dimmable at CRI 97 — one family across the whole house, each room at its correct temperature, everything rendering true.
