HEX vs RGB vs HSL vs CMYK: When to Use Each Format
Four ways to describe the exact same color, each built for a different job. Here's which one to reach for and why, comparing RGB, HSL, and CMYK side by side.
Pick any color and you can write it four different ways: #FF6B4A, rgb(255, 107, 74), hsl(11, 100%, 65%), or cmyk(0%, 58%, 71%, 0%). These aren't competing standards fighting for the same job — they're four different representations of light and ink, each optimized for a different context. The confusion isn't about which one is "correct." It's about not knowing which context calls for which format.
The four formats, one at a time
HEX
Hexadecimal notation packs the same red, green, and blue values RGB uses into a compact six-character code, two hex digits per channel (00 to FF, which is 0 to 255 in decimal). It's the default for static colors in CSS and HTML because it's short, universally supported, and every design tool exports it.
Best for: writing a fixed color value directly into CSS or HTML. Not ideal when you need to programmatically calculate a lighter or darker version — the math isn't intuitive in hex the way it is in HSL.
RGB
RGB is an additive color model: red, green, and blue light combined at different intensities (0 to 255 each). It's not just a notation choice — it's literally how a screen produces color, since each pixel is made of red, green, and blue sub-pixels lit at different brightness levels. This makes RGB the natural format when you're manipulating pixel data directly, like in a <canvas> element or an image-processing script.
Best for: JavaScript color manipulation, canvas APIs, anywhere you're working with raw pixel values. RGBA extends it with a fourth alpha channel for transparency.
HSL
Hue (0–360°, the position on a color wheel), Saturation (0–100%, how intense the color is), and Lightness (0–100%, how close to black or white). HSL was designed to match how people actually think about color — "make it lighter," "less saturated" — rather than how a screen renders it. That's exactly why this site's own palette generator works in HSL internally: generating a harmony rule or a tint/shade scale means adjusting hue and lightness predictably, which is straightforward in HSL and awkward in RGB or hex.
Best for: generating color variations, tints, shades, and harmonies programmatically; CSS hover/active states where you want a systematically lighter or darker version of a base color.
CMYK
Cyan, Magenta, Yellow, and Key (black), each as a percentage of ink coverage. Unlike RGB's additive light, CMYK is subtractive — inks absorb light reflected off paper rather than emitting it. This is the standard model for anything headed to a printing press, not a screen.
Best for: print design, and only print design. Converting RGB to CMYK is a lossy, approximate process, not a clean translation — some vivid RGB colors, especially bright blues and neons, simply can't be reproduced with ink and get remapped to the nearest printable equivalent, which usually looks duller than the original screen color. Always get a physical proof from your printer before finalizing a design based on a screen-converted CMYK value.
One color, four formats
Here's the same coral orange written all four ways — verified with this site's own color converter, so you can paste any of these values in yourself and see the others generate live.
Quick reference: which format for which job
| Context | Use | Why |
|---|---|---|
| Static CSS colors | HEX | Compact, universally supported, what every design tool exports by default |
| JavaScript / canvas pixel work | RGB or RGBA | Matches how the screen actually represents color; needed for direct pixel manipulation |
| Generating tints, shades, or hover states | HSL | Adjusting lightness or saturation is a simple, predictable number change; the same adjustment in hex or RGB isn't intuitive |
| Print design (flyers, packaging, business cards) | CMYK | Matches how ink actually reproduces color on paper; RGB doesn't translate directly to what a press can print |
Frequently Asked Questions
Are HEX and RGB the same color, just written differently?
Yes. HEX and RGB describe the exact same sRGB color value with no loss of precision — converting between them is a lossless, purely notational change, not a color shift.
Why does my color look different when I convert it to CMYK?
Because RGB and CMYK cover different gamuts — the range of colors each can represent. Some RGB colors, especially bright and saturated ones, fall outside what CMYK ink can reproduce, so the conversion approximates them with the nearest printable color. This is expected, not a bug in the conversion.
Can I convert between these formats without losing any color accuracy?
HEX, RGB, and HSL all describe the same RGB color space, so converting between those three is lossless. Converting to or from CMYK is the exception, since it's a genuinely different, narrower gamut built for ink rather than light.
Which format should I use if I'm not sure?
If it's staying on a screen, HEX is the safest default for CSS. If it's headed to a printer, convert to CMYK and get a proof before finalizing anything.
Sources
- RGB, HEX, and HSL conversion formulas — standard CSS Color Module algorithmsSee the CSS Color Module Level 4 specification.
- CMYK gamut limitations and screen-to-print color shiftWidely documented print-production behavior, not attributed to a single publisher.