Tool 02 — Color

CMYK / HEX / Lab Converter

Convert between CMYK, HEX/RGB and Lab D50. Approximates press colors using ICC profiles (Fogra39, Fogra51, SWOP v2). Generates Itten RYB harmony palettes and exports to ASE, CSS, JSON, or SVG. Results are approximations — for production-critical colour matching, verify against physical proofs.

Deeper Dive
CMYK to HEX: understanding color spaces for print and screen→

CMYK / HEX / Lab Converter

▶ Color Selection

Screen
HEX
RGB
R255
G0
B0
Lab D50
L53
a80
b67
Print
CMYK — sRGB
C0
M0
Y0
K0

How to use

Set a color using any input — type a HEX code, drag the RGB or Lab D50 sliders, pick a point on the wheel, or adjust CMYK. All inputs stay in sync.

Read precise values in Color Values below and copy directly to your clipboard: HEX, RGB, CSS, HSL, Lab D50, OKLCH, and ICC-adjusted CMYK for Fogra39, Fogra51 or SWOP v2.

▶ Color Values

HEX
#FF0000
RGB
255, 0, 0
CSS
rgb(255,0,0)
HSL
hsl(0, 100%, 50%)
HSB0° 100% 100%
Lab D50
53 80 67
OKLCH
oklch(…)
C0 %
M0 %
Y0 %
K0 %
sRGB: Mathematical model, accurate for screen. For press work use Lab mode to read Photoshop values directly.

▶ Color Harmonies — Itten RYB

Opposite colors on Itten's RYB wheel — Red↔Green, Yellow↔Violet, Blue↔Orange. Maximum contrast. Each shown with a darker and lighter variant.

Six adjacent hues on the RYB wheel (±30°, ±60°, ±90°). Harmonious and naturalistic — the colors neighbours in Itten's system.

Three hues equidistant on the RYB wheel (120° apart). Starting from Red, this gives Itten's three primaries: Red, Yellow, Blue. Each shown with a lighter variant.

Base color plus the two colors flanking its RYB complement (±30° around the opposite). More variety than pure complementary, slightly less tension.

Four hues forming a rectangle on the RYB wheel (90° intervals). Rich and complex — works best when one color clearly dominates. Shown with two tints.

Six luminance steps of the base hue — from deep shadow to near-white. Varied using Lab/LCH for perceptually even intervals. Refined and cohesive.

Build a free-form palette of up to six colors. Click + to add the current wheel color, or use → Copy to Custom in any harmony tab to start from there. Click any swatch to select it — all inputs then edit it live. Give each color a name — it carries through to all exports.

▶ Export Palette

Filename:
.ase

Why CMYK and HEX produce different colors

CMYK (Cyan, Magenta, Yellow, Key/Black) is a subtractive color model used in print: inks absorb light, so mixing them makes colors darker. HEX/RGB is an additive model used on screens: light is emitted, so mixing increases brightness. This means a vivid orange or neon green that looks striking on screen may appear duller in print — the CMYK gamut is smaller than sRGB, and some screen colors have no exact printable equivalent. This converter uses ICC profile approximation to give a directional CMYK reference; always verify separations with your RIP or profiled software before going to press.

What is Lab D50 and why does it matter for color conversion?

CIE Lab (also written L*a*b*) is a device-independent color space designed to represent colors as humans perceive them. The D50 white point matches the standard illuminant used in print and color management — it is the reference point for ICC profiles. Using Lab as an intermediate step in conversion (screen → Lab → CMYK) gives closer results than a direct sRGB-to-CMYK matrix because it accounts for the perceptual non-linearity of color vision. This tool uses Lab D50 as the intermediate color space for all cross-model conversions, and reports Lab D50 explicitly so you can pass the value directly to Photoshop or a spectrophotometer.

ICC profiles: Fogra39, Fogra51 and SWOP — and their limitations here

ICC profiles describe how a specific printing device or paper type reproduces color. Fogra39 (ISO Coated v2) is the standard for coated paper in European offset printing. Fogra51 (PSO Uncoated v3) covers uncoated and matte stock — it has a warmer paper white, higher dot gain and a smaller gamut than Fogra39. SWOP v2 is the North American equivalent for coated offset. Important: this tool simulates these profiles using a 16-corner lookup table — a significant simplification of the 80 000+ measured points in a real ICC profile. Solid primary inks typically fall within ±2–3 ΔE; mixed and midtone colors can deviate ±10–20 ΔE or more. Use the output as a directional reference. For production CMYK, assign the profile in Photoshop or Illustrator and soft-proof there.

Color harmonies on the Itten RYB wheel

The defined harmony palettes are generated on Johannes Itten's RYB (Red–Yellow–Blue) pigment wheel, the basis for classical color theory in painting, print and graphic design. In RYB, red and green are complementary, as are orange and blue, and yellow and violet — pairings that differ from the HSL wheel and correspond to the relationships taught in color theory. The six harmony types (complementary, analogous, triadic, split-complementary, tetradic, monochromatic) are read-only: they are defined by color theory rules, so the colors update automatically when you change the base color. The Custom tab lets you build a free-form palette of up to six colors by adding the current wheel color as swatches and editing each one individually.

Exporting palettes: ASE, CSS, JSON and SVG

All palette tabs — including Custom — export via the same four formats. Before downloading, choose whether to include RGB / HEX, CMYK, or both. ASE (Adobe Swatch Exchange) loads directly into the Swatches panel in Illustrator, InDesign and Photoshop; when CMYK is selected the swatches are embedded as CMYK color models. CSS exports as custom properties (--color-1 through --color-6); CMYK values appear as comments on each line. JSON includes HEX, RGB, HSL and Lab D50 — plus a cmyk field when selected. SVG exports a visual swatch strip with an optional CMYK line. Colors in the Custom palette can be named — those names carry through to every export format as the swatch name.

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Frequently asked questions

Is CMYK to HEX conversion exact?
No. CMYK and RGB/HEX represent different color gamuts. Many CMYK values have a close sRGB equivalent, but saturated print colors — especially certain reds, oranges and greens — fall outside the sRGB gamut and cannot be reproduced accurately on a standard screen. The converted value is the closest sRGB equivalent, not an identical match.
How accurate are the Fogra39, Fogra51 and SWOP values?
These profiles are simulated using a 16-corner lookup table — a significant simplification of a real ICC profile (which typically contains over 80 000 measured points). Solid primary inks (100% C, 100% M, etc.) typically fall within ±2–3 ΔE. Mixed and midtone colors can deviate ±10–20 ΔE or more, depending on how far the color sits from a primary. Use the output as a directional reference to understand how a color will shift on a given substrate. For production-ready CMYK separations, use Photoshop or Illustrator with the ICC profile properly assigned.
Which ICC profile should I use for my print file?
For commercial printing in Europe on coated paper (brochures, posters, magazines), use Fogra39. For uncoated stock (flyers, letterhead, some packaging), use Fogra51. For North American coated offset printing, use SWOP v2. When in doubt, ask your print supplier which profile they require — many European printers specify ISO Coated v2 (Fogra39) in their file submission guidelines.
Why are the color harmonies based on the RYB wheel and not the HSL wheel?
The HSL/RGB color wheel is a mathematical model for screen color mixing — it distributes hues evenly by wavelength. The Itten RYB wheel is a perceptual model rooted in pigment mixing and classical color theory, where the primary colors are red, yellow and blue. In RYB, the complementary pairs (red/green, orange/blue, yellow/violet) correspond to the pairings used in painting, print design and traditional color education. For design work that bridges print and screen, the RYB wheel produces harmonies that feel correct to a trained eye and match the color relationships described in Itten's The Art of Color.
How does the Custom palette tab work?
The Custom tab in Color Harmonies lets you build a free-form palette of up to six colors. Click + to add the current wheel color as a swatch, or use → Copy to Custom in any defined harmony tab to start from those colors. Click any swatch to select it — all inputs (wheel, HEX, RGB, Lab, CMYK sliders) then edit that swatch live in real time. Give each color a name: the name carries through to all exports as the ASE swatch name, the CSS comment, and the JSON role field. Click the swatch again to deselect. Remove swatches with the × button.
What does the RGB / CMYK checkbox in Export do?
The checkboxes control which color model each download contains. RGB / HEX (on by default) exports colors as HEX values in CSS and JSON and as RGB model swatches in ASE. When CMYK is also checked, CSS files include the CMYK breakdown as a comment, JSON files add a cmyk field, SVG files show CMYK values under each swatch, and ASE files include CMYK model swatches alongside (or instead of) the RGB ones. CMYK values use the ICC profile currently selected in the Color Values panel — the label next to the CMYK checkbox updates automatically.
What is the difference between Lab and OKLCH?
Both are perceptually uniform color spaces. Lab uses rectangular coordinates (lightness, green-red axis, blue-yellow axis). OKLCH uses polar coordinates (lightness, chroma, hue angle) — which makes it more intuitive for designers, since hue and saturation are separate knobs. OKLCH is the newer standard and is supported in modern CSS via the oklch() function.
Can I import the ASE file into Figma?
Figma does not natively import ASE files. Use the Palette Importer community plugin to import ASE swatches into your Figma document.
Why does my Pantone color look different on screen?
Pantone spot colors are mixed inks, not CMYK combinations, and many have no exact CMYK or RGB equivalent. Pantone publishes official HEX approximations for screen use, but these are visual approximations only — the on-screen rendering depends on display calibration, viewing conditions and the operating system's color management.
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Disclaimer — Tool 02 · CMYK / HEX / Lab Converter
Intended Use
This tool is designed for screen design and as a directional reference for print work. Color values, especially ICC profile output, are indicative only. They are not a substitute for professional color management with embedded ICC profiles in Photoshop, Illustrator or a RIP workflow.
CMYK sRGB Model
The default CMYK sliders use a mathematical sRGB formula. This model does not account for dot gain, ink absorption, or substrate properties. Results will differ from press output. Always verify CMYK values with your print supplier's profiled workflow before committing to production.
ICC Profile Accuracy — Important
Fogra39, Fogra51, and SWOP v2 values are simulated using a 16-corner lookup table — a severe simplification of the 80 000+ measured points in a real ICC profile. Solid primary inks: ±2–3 ΔE. Mixed and midtone colors: ±10–20 ΔE or more. Treat these as coarse directional guidance, not production-ready separations. For press-accurate CMYK, use Photoshop or Illustrator with the embedded ICC profile assigned.
Lab D50 Input
Entering Lab D50 values read directly from Photoshop (using D50 mode) gives the most press-relevant screen representation this tool can provide. The Lab→RGB conversion is mathematically exact; screen appearance still depends on your display calibration and color profile.
Color Harmony Palettes
Defined harmony palettes (Complementary, Analogous, etc.) are generated algorithmically by rotating hue on the Itten RYB wheel. Use → Copy to Custom in any harmony tab to move the palette to the Custom editor. The Custom palette supports naming individual swatches; names carry through to all exports. All results are suggestions, not design decisions — adjust and verify colors for your specific context.
Liability
All outputs are provided without warranty of any kind, express or implied. uicorn and its operator accept no liability for any direct, indirect, or consequential loss or damage arising from the use of, or reliance on, this tool or its output. You are solely responsible for verifying all values before use in any professional, commercial, or production context.