Ideas & guides · Lighting
Warm White or Cool White Christmas Lights?
Half the boxes say warm white and half say cool white, they cost the same, and the pictures on the front look identical. Does it matter?
Pick one and buy everything in it. Warm white is the traditional, candle-coloured look and it flatters brick, wood and greenery. Cool white is blue-tinted and it reads as snow and ice. Mixing them within one yard is what makes a display look like it was assembled over three years, because that is usually what happened.
4 minute read.
What the two actually are
Warm white is around 2700 kelvin, which is roughly the colour of an old filament bulb or a candle. Cool white runs from about 5000K upward and has a blue cast to it. Manufacturers also sell "pure white" and "bright white", which sit between the two and are not a standard, so the only reliable way to know is to look at the kelvin figure rather than the adjective.
On their own, either looks correct. Your eye adjusts to whichever it is given and accepts it as white within a few seconds.
Side by side it cannot. Put a warm run next to a cool one and the warm one instantly looks dirty yellow and the cool one looks like a security floodlight. Neither is flattering and neither was what you bought.
Which one suits what you already own
| Your house is | Better bet | Why |
|---|---|---|
| Red or orange brick | Warm white | Cool white turns warm brick a muddy pink. Warm light sits in the same part of the spectrum the brick already reflects. |
| Wood, log or stained siding | Warm white | Same reason, more so. Cool white drains the colour out of timber completely. |
| White, gray or pale render | Either, and cool is striking | A pale wall has nothing to be drained out of it, so cool white reads as crisp rather than clinical. |
| Surrounded by evergreens | Warm white | Cool white makes dark green foliage read as near-black. Warm light keeps it green. |
| Actually snowy in December | Cool white | This is the one case where cool is the honest choice, because it matches the ground. |
If you already own both
Do not try to blend them. Separate them by surface instead: all the roofline one tone, all the ground the other, with nothing in between carrying a mix. Read as two deliberate layers it can work. Read as a random scatter it never does.
The better fix, if you are replacing anything anyway, is to standardise one surface at a time. The roofline first, because it is the longest continuous run and the one where a tone change halfway along is unmissable.
And buy the whole run in one go where you can. Even within a single tone, sets bought two years apart from the same maker are often visibly different, because LED bins shift between production runs.
The same set in both tones
These are the same fixture with different diodes, within a dollar of each other, so the choice really is only the colour.
| What | Size | Price | Where |
|---|---|---|---|
|
C9 LED Warm White String Light Set, 25 bulbs 2700K-ish, 16 ft lit. The default, and the safer one on brick or timber. |
3" H 16' W |
$26.98 | Home Depot (opens in a new tab) |
|
C9 LED Cool White String Light Set, 25 bulbs Same 16 ft lit run, blue-white. Good on a pale wall or a genuinely snowy December, wrong on red brick. |
3" H 16' W |
$27.98 | Home Depot (opens in a new tab) |
|
Cool White Icicle Lights, 33 ft, 400 LEDs 33 ft lit. Icicles are the one place cool white is almost always right, because the thing being imitated is ice. |
1' 6" H 33' W |
$26.99 | Amazon (opens in a new tab) |
Prices are what the retailer listed when it was last checked. They move, especially in the last three weeks before a holiday.
Before you commit to a whole house, plug one set in at dusk and stand at the sidewalk, not on the lawn. Warm and cool look far more similar up close than they do at forty feet in the dark, which is the only distance that matters. This is also the fastest way to discover your neighbour has the other one.
Where this usually goes wrong
Buying by the word on the box
"Bright white" and "pure white" are marketing rather than measurements, and two brands will not mean the same thing by them. Find the kelvin number. Under 3000K is warm, over 5000K is cool, and the middle is where the confusion lives.
Topping up a run with whatever the shop has left
A roofline that changes tone two thirds of the way along is the most obvious lighting mistake there is, and it happens every year to people who ran one set short. Buy the whole run at once, or move the odd set to a different surface.
Mixing tones and calling it warm
Warm and cool do not average out into something pleasant at distance. They stay visibly two colours, and the display reads as unfinished rather than as layered.
Every plan on this site keeps one tone per yard for exactly this reason, and the shopping list records the tone of each set so a mixed one cannot slip in by accident.
Read next
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Each one is a lot shape or a problem worked all the way through, the same as this one, and they are all free to read. No schedule worth promising, but they keep coming.