Convertisseur d'unités et couleurs CSS

Comprendre les couleurs et unités CSS

Formats de couleur HEX, RGB et HSL

CSS prend en charge plusieurs formats de couleur. <strong>Les couleurs HEX</strong> utilisent une notation hexadécimale à six caractères (ex. <code>#22c55e</code>).

<strong>RGB (Rouge, Vert, Bleu)</strong> utilise des valeurs décimales de 0 à 255 pour chaque canal.

<strong>HSL (Teinte, Saturation, Luminosité)</strong> est le plus intuitif pour les designers.

CSS Named Colors

CSS provides 147 named colors like coral, steelblue, and rebeccapurple. While convenient for prototyping, named colors offer limited precision. Converting a CSS color name to HEX or RGB gives you exact values you can fine-tune for production use.

CMYK pour l'impression

<strong>CMYK</strong> est le modèle de couleur standard pour l'impression. Convertir les couleurs web en CMYK aide à préparer les fichiers pour la production.

HSV dans les outils de design

<strong>HSV</strong> est le modèle de couleur natif dans des outils comme Photoshop, Figma et Sketch.

OKLCH — CSS Color Level 4

OKLCH (Lightness, Chroma, Hue) is the modern perceptually uniform color space introduced in CSS Color Level 4. Unlike HSL, OKLCH ensures that colors with the same lightness value actually appear equally bright to the human eye. It's supported in all modern browsers and is becoming the preferred format for design systems that need consistent, predictable color palettes.

LCH — CIE LCH Color Space

LCH (Lightness, Chroma, Hue) is the cylindrical representation of the CIELAB color space. It provides perceptually uniform color differences, meaning equal numerical changes produce visually equal differences. LCH is supported in CSS Color Level 4 via the lch() function and is widely used in color science, print workflows, and advanced design systems.

LAB — CIELAB Color Space

CIELAB (L*a*b*) is a device-independent color space that models human vision. L represents lightness (0–100), while a and b represent color-opponent dimensions (green–red and blue–yellow). LAB is the foundation for Delta E color difference calculations and is essential for color matching, print proofing, and scientific color analysis.

HWB — Hue Whiteness Blackness

HWB (Hue, Whiteness, Blackness) is a CSS Color Level 4 format designed to be more intuitive than HSL. You start with a hue, then add whiteness to lighten and blackness to darken. It's supported via the hwb() function in modern browsers and is particularly useful for creating tints and shades without complex math.

Tailwind CSS Colors

Tailwind CSS ships with a comprehensive color palette organized by name and shade (e.g., blue-500, rose-400). Converting Tailwind color classes to HEX codes is essential when integrating Tailwind designs with external tools, creating custom themes, or working with design tools that require hex values.

PX vs REM : Unités CSS expliquées

<strong>Les pixels (PX)</strong> sont des unités absolues. <strong>REM</strong> est relatif à la taille de police de l'élément racine (généralement 16px).

La conversion est simple : divisez les pixels par 16 pour obtenir les valeurs REM.

<strong>Les unités EM</strong> sont relatives à la taille de police de l'élément parent, contrairement au REM qui référence la racine.

• 1rem = 16px (default browser setting)
• 1em = parent font-size (context-dependent)
• 0.75rem = 12px — common for small/caption text
• 1.25rem = 20px — common for subheadings
• 2rem = 32px — common for section headings

Pourquoi utiliser des convertisseurs CSS ?

Convertir manuellement entre les formats de couleur est fastidieux et sujet aux erreurs.

• Instant results — paste a value and get the converted output immediately, no formulas needed.
• Copy-ready output — every result includes a one-click copy button with properly formatted CSS syntax.
• Color preview — see a live swatch of the converted color to visually confirm accuracy.
• No installation — works in any browser, on any device. No extensions, downloads, or signups.
• Developer-friendly — shareable URLs with pre-filled values for easy team collaboration.

Common CSS Conversion Workflows

• Design handoff: Figma and Sketch export colors as HEX. Convert to RGB or HSL if your codebase uses those formats.
• Dark mode generation: Take your light-mode HSL palette, adjust lightness values, and convert back to HEX.
• Accessibility checks: Convert colors to RGB to calculate contrast ratios using the WCAG luminance formula.
• Legacy migration: Convert pixel-based layouts to rem-based responsive systems during refactors.
• Cross-browser debugging: Quickly convert colors to match your source code format.

Supported Conversions