Short answer
NCS describes colours by how they look in relation to six elementary colours that people perceive as pure — white, black, yellow, red, blue and green — rather than by pigment amounts or light measurements. A notation such as S 1040-R20B means 10% blackness, 40% chromaticness and a red hue with 20% resemblance to blue. Developed in Sweden from Hering's opponent-colour theory and launched with an atlas in 1979, when it became the Swedish reference for colour designation, it is widely used in architecture and interiors.
Licensing: NCS is a commercial system; its colour data is not reproduced by Colourwise.
NCS is built on Ewald Hering's observation that some colours look 'pure' — a unique yellow with no hint of red or green, a unique red with no yellow or blue — and that every other colour is judged by its resemblance to them. The six are white, black, yellow, red, blue and green. Hues are placed on a circle divided into four quadrants between the chromatic elementary colours, so Y50R is a hue equally resembling yellow and red, and R20B is a red with 20% resemblance to blue. Unlike Munsell, NCS does not aim for equal visual steps; it aims for descriptions that match what people say they see.
In S 1040-R20B, the S indicates a standardised sample; 10 is blackness (resemblance to black) and 40 is chromaticness (resemblance to the pure hue), which together are called the nuance; R20B is the hue. Whiteness is not written because the three add to 100, so this colour has 50% whiteness. Neutrals — whites, greys and blacks — have no hue and are written with -N in place of the hue. Because the numbers describe appearance, an experienced reader can picture a colour from its code: a high first pair means dark, a high second pair means strong colour, and the hue letters say which way it leans.
The system's own history traces the idea to Swedish research in the 1930s and 1940s on Hering's theory, and to psychophysical work in the 1960s and 1970s by Anders Hård, Lars Sivik and Gunnar Tonnquist, based on many thousands of visual judgements. The NCS Atlas was launched in 1979 with 1,412 standard colours, and NCS became the Swedish reference for colour notation the same year; Norway, Spain and South Africa later adopted it too. The collection grew to 1,750 colours in 1995, 1,950 in 2004 and 2,050 in 2022, the last expansion adding neutrals.
NCS is strongest where colours are chosen and communicated by eye: architects, interior designers and paint retailers use it because a code conveys how light, how strong and which hue without a colour chart. It is weaker as a measurement space: NCS coordinates are not perceptually uniform, so equal numerical differences are not equal visual differences, and colour-difference tolerances are still computed in CIELAB. NCS reference samples and conversion data are commercial products of NCS Colour AB; Colourwise explains the notation but does not reproduce NCS colour values.
| Part | Meaning | Value in this example |
|---|---|---|
| S | Standardised sample | Standard NCS edition |
| 10 | Blackness (resemblance to black) | 10% |
| 40 | Chromaticness (resemblance to the pure hue) | 40% |
| (implied) | Whiteness = 100 − blackness − chromaticness | 50% |
| R20B | Hue: red with 20% resemblance to blue | A slightly bluish red |
Each statement is labelled by kind — established fact, a standard’s requirement, observed market data, a convention, or Colourwise’s own interpretation or analysis — with the strength of the evidence behind it.
FactStrong evidence
NCS describes colours by blackness, chromaticness and hue relative to six elementary colours (white, black, yellow, red, blue and green); in S 1040-R20B, 10 is blackness, 40 chromaticness and R20B a red with 20% blue.
Source: The NCS system
FactModerate evidence
The NCS Atlas was launched in 1979 with 1,412 standard colours, expanded to 1,750 in 1995, 1,950 in 2004 and 2,050 in 2022, following psychophysical research by Hård, Sivik and Tonnquist.
Caveat: The system owner's own account.
Source: The history of NCS Colour
FactModerate evidence
NCS has been the reference norm for colour designation in Sweden since 1979, and has been adopted as a national reference in Norway, Spain and South Africa.
Caveat: Reference-work source; national standard numbers and current status not independently verified.
Source: Natural Color System (Wikipedia)
Reviewed 29 September 2026. Colourwise summarises its sources in its own words and does not reproduce standards text or proprietary colour data. Spotted an error? Tell us.