What the kelvin number means
Every LED bulb and fixture lists a colour temperature in kelvin (K). It describes whether white light looks warm and amber or cool and bluish. The lower the number, the warmer the light.
It has nothing to do with heat or brightness. A 4000K light is not hotter or brighter than a 2700K light. It just looks whiter.
| Label on the box | Kelvin | How it feels |
|---|---|---|
| Warm white | 2700K | Cozy, like an old incandescent bulb |
| Soft white | 3000K | Warm but crisper, flatters most finishes |
| Neutral white | 3500K to 4000K | Clean and alert, good for work |
| Daylight | 5000K and up | Very white, can feel clinical indoors |
Choosing for each space
Homes. Most living rooms and bedrooms feel best at 2700K or 3000K. Kitchens and bathrooms often go to 3000K, sometimes 3500K for a crisper look on white cabinets and quartz. Garages, workshops and laundry rooms can handle 4000K or more, where seeing detail matters more than mood.
Businesses. Offices usually land on 3500K to 4000K. Retail depends on the product: warmer for restaurants, furniture and fashion, neutral for grocery and hardware. Warehouses and shops commonly use 4000K to 5000K. Our office lighting design guide goes further.
Outdoors. Warmer light, 3000K or below, produces less glare and less sky glow, which neighbours appreciate. See outdoor security lighting for more.
Think about when the space is used. Edmonton winter evenings start before five o'clock, so home lighting does most of its work in the dark hours when warm light feels most restful. A shop or office that runs mostly in daylight can lean cooler without feeling harsh.
Buy one bulb of each option and live with them for an evening. Light that looks fine in a store can feel harsh at 9 p.m. on a dark December night.
CRI and R9: how true colours look
Colour rendering index (CRI) measures how faithfully a light shows colours compared with a reference source, on a scale up to 100. Most basic LEDs are around CRI 80. Better products are 90 or higher.
CRI is an average of several colour samples, and it leaves out the one that matters most for people and food: R9, saturated red. A lamp can score CRI 80 while rendering reds poorly, which makes skin look sallow and wood floors look flat.
- For kitchens, bathrooms, dining rooms and retail, look for CRI 90 or higher and a positive R9 value on the spec sheet.
- For warehouses, parking areas and utility spaces, CRI 80 is usually fine.
- If a spec sheet does not list R9, ask for it or choose a product that does.
Keep colour consistent
Nothing looks worse than a ceiling of pot lights where one is pinkish and the next is greenish. That happens when products are mixed, or when cheaper LEDs vary from batch to batch.
- Use the same brand and product line throughout a room.
- Check colour consistency on the spec sheet, often listed in MacAdam ellipse steps or SDCM. Three steps or fewer is tight enough for most homes and offices.
- Buy a few spares at the same time so a future replacement matches.
- Match kelvin between pot lights, under-cabinet strips and pendants in the same space.
Warm dim and tunable white
Standard LEDs keep the same colour as you dim them, so a dimmed 3000K light just looks like a weak 3000K light. Warm dim (also called dim-to-warm) products shift towards amber as they dim, the way old halogen bulbs did. They are great in dining rooms, bedrooms and restaurants.
Tunable white fixtures let you set the colour temperature with a control, cooler during the day and warmer at night. They suit offices, care homes and classrooms, and they need compatible controls, so plan them with your electrician rather than adding them later.
Warm dim and tunable products only work as advertised on the controls they were tested with. Read our dimmer compatibility guide before you buy.
Common questions
Is 3000K or 4000K better for a kitchen?
Most homeowners prefer 3000K, which feels warm but still crisp. 3500K suits very white, modern kitchens. 4000K can feel cold in a home at night, though some people like it.
Does a higher kelvin number mean brighter light?
No. Brightness is measured in lumens. Kelvin only describes the colour of the light. Two lamps with the same lumens look equally bright at 2700K or 4000K, although cooler light can feel brighter to some people.
What CRI should I ask for?
CRI 90 or higher with a positive R9 value for living spaces, kitchens, bathrooms and retail. CRI 80 is generally fine for warehouses, garages and parking areas.
Can I mix 2700K and 3000K in the same room?
It is better not to in the same fixture type. Small differences show up side by side, especially on white ceilings. Different layers, such as a warm table lamp and neutral pot lights, can work if done on purpose.
Codes and permit rules change and every building is different. For work on your system, talk to a licensed electrician and your local permit authority.