RAL 5015 in CMYK: C81 M37 Y0 K30

If you searched "RAL 5015 in CMYK," here is the number: C81 M37 Y0 K30. That is the cyan, magenta, yellow, and black a press loads to reproduce Sky blue. The figure is easy to get. The useful part is knowing how far to trust it and how to print it so the sheet holds up next to the coated part.

This post takes the one colour apart: where the build comes from, why it carries no yellow at all, and why even a flawless print lands a shade off the physical RAL chip. For the live lookup of any other RAL code, the RAL to CMYK converter does the calculation; this is the story behind the single query that brings most people here.

RAL 5015 in CMYK: the build

RAL 5015 has one published sRGB reference: rgb(34, 113, 179), written as #2271B3. Run that through the standard RGB-to-CMYK inversion and it collapses to a single answer, C81 M37 Y0 K30. There is no range of valid builds and no nearest-match list, because the colour maps to exactly one RGB value to begin with.

The direction matters here. Going the other way, the CMYK to RAL converter has to report a distance score, since it squeezes a continuous range of CMYK onto a finite set of coating chips and picks the closest. RAL to CMYK has nothing to squeeze. The same code returns the same build every time, which is why the two tools behave so differently for what looks like the same job.

A derived value, not an official RAL spec

Deterministic is not the same as official. RAL certifies physical colour chips and publishes RGB and HEX references for digital use, but it issues no official CMYK table. C81 M37 Y0 K30 is a derived value: the published RGB pushed through a device-independent formula that carries no ICC profile. It is a starting build for the press, not a colour-managed match.

The practical consequence is to never write "official RAL 5015 CMYK" on anything. On a spec sheet, quote the RAL code itself. That code is what a coater or print buyer matches against a physical fan deck, and it survives being handed to a second supplier without your file. The CMYK build is a convenience for whoever runs the press.

No yellow at all: a quirk of the conversion

Look at the build again and one number stands out: yellow is zero. A mid-blue with no yellow ink surprises people, but it falls straight out of the math. Blue (179) is the brightest of the three channels for this colour, and the conversion sets the black channel from whichever channel is brightest, about 30% here. Yellow is computed from the blue channel, which was already the maximum, so it lands at exactly 0. The result is a clean cyan-magenta-black build, as the channel chart below shows.

This is also where the derived value and a real press part company. A production profile using grey-component replacement will not leave yellow at zero; it redistributes ink and usually adds a few points of yellow to give the blue more body and stop it reading flat. So if a print shop's RAL 5015 build shows a little yellow, that is not an error, it is the profile doing its job. The naive 0 is the honest starting point, not the finished recipe.

Why the printed sheet won't match the chip

RAL 5015 lives as paint on an opaque, usually semi-matt surface: a powder-coated panel or a sprayed finish. The CMYK build lives as a thin film of ink sitting on paper. Those two surfaces send light back to your eye differently. The coating scatters and reflects across its whole depth, while ink lets the paper white show through. Even a perfect C81 M37 Y0 K30 print reads a touch flatter and cooler than the fan-deck chip, and that gap is physical, not a rounding error you can dial out.

Paper shifts it further. A bright white coated stock keeps the blue crisp; an off-white or uncoated sheet pulls it toward grey. Before you trust any print, run the CMYK test page on the same printer: a weak cyan channel quietly drags every blue toward purple, and you want to catch that before the production file. For the wider picture of which screen colours survive the trip to ink at all, the RGB vs CMYK guide covers the gamut side in depth.

A workflow for printing RAL 5015 accurately

Getting the colour onto paper well is four short steps:

1. Look up the build. Read RAL 5015 as C81 M37 Y0 K30 from the RAL to CMYK converter. One code, one value.
2. Type the numbers into a CMYK swatch. Enter 81, 37, 0, 30 directly. Do not pick a sky-blue from an RGB wheel and let the app convert it for you, which produces a different recipe.
3. Soft-proof under your press profile.The build is profile-relative, so switch the document's working CMYK profile to the one your printer publishes and preview the shift on screen.
4. Pull a hard proof on the real stock. Compare it against the RAL fan deck in good light before you sign off the run.

RAL is one of several systems a colour might be specified in. If you are mapping RAL against Pantone, NCS, and the RGB/CMYK split for a brand, the color guide hub lays out how each system fits and which tool to reach for.