Same 3000K, different white. Why two LED strips don't match

Two reels of LED strip, both labelled 3000K. Installed side by side on one gallery wall, they don't match: one leans green, the other pink. Nobody did anything wrong on site. The label simply never promised more than it says.

It is one of the most common complaints in linear lighting, and it is avoidable if the colour is specified properly before the order.

Why the same CCT can look different

CCT (correlated colour temperature) describes where a white sits between warm and cool. It is a single number, and many slightly different whites share it. Two light sources can both be "3000K" while one sits a little above the ideal white line (towards green) and the other a little below it (towards pink or magenta).

On their own, both look like warm white. Put them next to each other on a continuous surface, a pale plaster wall, a stone counter or a long cove, and the eye compares them directly. That is when the difference shows.

What actually defines the colour

To pin a white down, three things need to be agreed, not just the Kelvin value:

• Chromaticity coordinates. The exact position of the white on the colour chart, not only its temperature.
• Permitted colour variation. How far a strip may drift from that target. It is usually expressed in SDCM steps (MacAdam ellipses): the smaller the number, the closer the LEDs must be to each other. Our reference AS2835 strip specifies SDCM <3.
• The LED bin. LEDs are sorted into bins by colour after manufacture. Strips built from the same bin match each other; strips from neighbouring bins may not.

As our technology page puts it: define target CCT, chromaticity coordinates and permitted colour variation, match the LED bin, and approve a physical sample against the actual stone, timber, fabric or adjacent luminaire.

What helps

1. Specify chromaticity and SDCM, not just CCT. "3000K" on a drawing leaves the colour open. A target and a tolerance close it.
2. Approve a physical sample next to the real material. A white that looks right on a white card can look wrong on travertine or walnut. Screens and printed colour swatches are no help here.
3. Keep one bin across a continuous line. A long cove or a run of showcases should be built from one LED bin. Record that bin, so a reorder or a replacement section can be matched later.
4. Order the whole line at once where you can. Splitting one visible line across several orders makes matching harder, even with a recorded bin.

Where it matters most

Mismatch is most visible where light lands on large, even, pale surfaces and where the eye can compare two sections directly: gallery walls, hotel corridors, retail shelving, jewellery counters and continuous coves. In those spaces a tight colour tolerance is worth specifying from the start.

How we approach it

For project and OEM work, the colour target is agreed before production, not discovered on site. Tell us the CCT, the tolerance and the materials the light will fall on, and we will prepare samples for approval. You can start with the colour section of our technology page or send us your project.