HEX to CMYK Converter

Brand colors usually start as HEX codes, but business cards, brochures and signs need CMYK values for the print brief. This converter takes a whole palette at once — one color per line, optionally with a label such as "Primary #1E90FF" — and returns CMYK rounded to whole percentages, the way style guides list them. It also converts each rounded value back to HEX and measures the color shift (ΔE2000), adds up the total ink and draws labelled swatches. It works the other way too: paste CMYK values and get HEX codes.

How to use this tool

1. Paste your colors, one per line; add a label before each code if you like.
2. Keep whole percent for a style guide, or choose one decimal.
3. Copy the CMYK list, and check the shift column — anything under 1 is invisible.
4. For CMYK → HEX, switch the direction and paste four numbers per line.

Formula

K = 1 − max(R′, G′, B′) · C = (1 − R′ − K) ÷ (1 − K) · M = (1 − G′ − K) ÷ (1 − K) · Y = (1 − B′ − K) ÷ (1 − K) · back: R = 255 × (1 − C) × (1 − K)

R′, G′, B′ are the channels divided by 255. The rounded CMYK is converted back with the second formula, and ΔE2000 compares that color with the original in CIELAB. This is the profile-free conversion design tools show as a starting point; presses use ICC profiles.

Example

The default five-color palette becomes Primary #1E90FF → C88 M44 Y0 K0, Accent #FF6347 → C0 M61 Y72 K0, Success #2E8B57 → C67 M0 Y37 K45, Text #333333 → K80 and Background #F5F5F5 → K4. Rounding moves Primary the most: C88 M44 Y0 K0 converts back to #1F8FFF, a ΔE2000 of 0.37 — far below what anyone can see — and Accent comes back exactly as #FF6347.