NCS or RAL — which do I give the painter?
Give NCS for wall paint and RAL for metal and industrial finishes. Either way, the code goes in writing — never a photograph of a sample.
Krizbai András · Last verified: August 2026
NCS (Natural Colour System) suits wall paint because it describes colour the way the eye perceives it. The code is not a recipe but a perception: how much blackness, how much chromaticness, and which hue. S 2010-Y30R means 20% blackness, 10% chromaticness, a hue between yellow and red, 30% of the way from yellow. The NCS Index 2050 edition holds 2,050 standardised colours, and every major paint manufacturer's tinting machine reproduces them.
RAL belongs on metal and industrial finishes because there the code is tied to a manufacturing system. RAL Classic dates from 1927 and now runs to over two hundred four-digit colours — it is the language of powder coating, metalwork, windows and plant. A metal fabricator or a coating plant expects RAL, not NCS. Where Classic is too coarse, RAL Design plus offers a finer, CIELAB-based division.
Codes are issued in writing; never as a photograph of a sample. A colour sample photographed on a phone distorts at three points: the white balance of the capture, the sender's screen and the recipient's screen. The same photograph is two different colours on two devices. This is not carelessness — a photograph physically does not carry the colour data.
Pro tip: the client should own a colour card too. A RAL K7 fan deck, and an NCS Index fan for wall paint, put both sides on the same language. When the designer says RAL 7016, the client does not have to imagine it — they open the fan and look. A conversation that would otherwise take two rounds of email and one misunderstanding takes thirty seconds. The cost is negligible against any project budget and pays for itself the first time it prevents a repaint. For large surfaces it is worth looking at RAL K5 as well: the chips are larger, so the saturation of a big area starts to show — the fan deck is for the conversation, the large-chip card is for the decision.
Ren Design visualisations are built from NCS→RGB and RAL→RGB conversions, not from colours mixed by eye. Every surface in the render traces back to a code, and it is the code that goes into the construction drawings and to the painter — not the shade seen on screen. This does not make the render colour-accurate. It makes it referenceable.
The conversion is an approximation, not an identity. A screen emits light; a wall reflects it. The sRGB gamut cannot display every paint colour, and no two monitors are calibrated alike. Two further things the code does not carry: gloss level — the same code reads as a different shade in matt and in satin — and surface area, because a large wall reads more saturated and darker than the same colour on a palm-sized chip.
This is why physical sampling cannot be skipped. Colour has to be seen in the room and the material has to be handled. The reliable procedure is a sample board of at least A3, painted in the final gloss level, viewed on site in both daylight and evening light — not under paint-shop lighting, and not from an A6 colour card. A colour card does not settle everything either: the card is printing ink, the wall is paint. The card is the tool for the conversation; the sample board is the tool for the decision. The same applies to every other material: stone, veneer and textile have to be touched, because touch carries information about colour too.
When specifying colour, avoid these: sending a photograph instead of a code; giving NCS to a coating plant; giving RAL for an interior wall; omitting the gloss level alongside the code; deciding a large wall from a small chip; and approving a sample board under paint-shop lighting.
The colour code belongs to the drawings; sampling belongs to approval. How we work →