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OKLCH vs HSL: Why You Should Make the Switch

A detailed comparison between OKLCH and HSL color spaces. Understand the limitations of HSL and why OKLCH provides better color consistency and perceptual uniformity.

OKLCH vs HSL: Why You Should Make the Switch

If you've been using HSL (Hue, Saturation, Lightness) for years, you might be wondering: "Why should I switch to OKLCH?" This article breaks down the key differences and shows why OKLCH is superior for modern web design.

The Fundamental Problem with HSL

HSL was designed as a more intuitive alternative to RGB, and in many ways, it succeeded. The ability to manipulate hue, saturation, and lightness independently seemed like a game-changer. However, HSL has a critical flaw: it's not perceptually uniform.

What Does "Not Perceptually Uniform" Mean?

Let's look at a simple example. All these colors have the same HSL lightness value of 50%:

.yellow { color: hsl(60deg 100% 50%); }   /* Appears very bright */
.blue { color: hsl(240deg 100% 50%); }    /* Appears much darker */
.red { color: hsl(0deg 100% 50%); }       /* Somewhere in between */

Even though they all have 50% lightness, they don't look equally bright to the human eye. Yellow appears significantly lighter than blue, which means:

  • ❌ You can't create consistent color palettes by just adjusting lightness
  • ❌ Ensuring accessibility compliance is harder
  • ❌ Color manipulations produce unexpected results
  • ❌ Animations between colors look uneven

How OKLCH Solves This

OKLCH is based on human perception. When colors have the same lightness value in OKLCH, they actually look equally bright:

.yellow { color : oklch(0.85 0.20 100); }  /* Perceptually consistent */
.blue { color: oklch(0.85 0.20 250); }     /* Same perceived brightness */
.red { color: oklch(0.85 0.20 30); }       /* Same perceived brightness */

Now all three colors appear equally bright because OKLCH lightness matches human vision.

Side-by-Side Comparison

Creating a Color Palette

With HSL (Inconsistent)

/* HSL palette - looks uneven */
.primary-100 { background: hsl(240deg 100% 95%); }
.primary-200 { background: hsl(240deg 100% 85%); }
.primary-300 { background: hsl(240deg 100% 75%); }
.primary-400 { background: hsl(240deg 100% 65%); }
.primary-500 { background: hsl(240deg 100% 55%); }
.primary-600 { background: hsl(240deg 100% 45%); }
.primary-700 { background: hsl(240deg 100% 35%); }

Problem: The perceived difference between shades is not consistent. Early shades (100-300) look too similar, while later shades (500-700) have jarring jumps.

With OKLCH (Consistent)

/* OKLCH palette - perfectly even progression */
.primary-100 { background: oklch(0.95 0.15 250); }
.primary-200 { background: oklch(0.85 0.15 250); }
.primary-300 { background: oklch(0.75 0.15 250); }
.primary-400 { background: oklch(0.65 0.15 250); }
.primary-500 { background: oklch(0.55 0.15 250); }
.primary-600 { background: oklch(0.45 0.15 250); }
.primary-700 { background: oklch(0.35 0.15 250); }

Result: Every shade has exactly the same perceived difference from the next, creating a harmonious palette.

Ensuring Accessibility

With HSL (Difficult)

/* Is this accessible? Hard to tell visually */
.container {
  background: hsl(210deg 50% 90%);
  color: hsl(210deg 50% 30%);
  /* 60 percentage point difference, but is the contrast sufficient? */
}

You need to:

  1. Convert to RGB
  2. Calculate relative luminance
  3. Check contrast ratio
  4. Adjust and repeat

With OKLCH (Easy)

/* Much easier to ensure contrast */
.container {
  background: oklch(0.90 0.05 250);  /* Light background */
  color: oklch(0.30 0.08 250);       /* Dark text */
  /* 0.60 lightness difference = good contrast */
}

Rule of thumb: A lightness difference of 0.40 or more typically ensures WCAG AA compliance.

Color Manipulation

Lighten/Darken with HSL

/* Base color */
--primary: hsl(240deg 70% 50%);

/* Lighter version - just increase lightness? */
--primary-light: hsl(240deg 70% 70%);
/* Result: Looks washed out and less saturated */

/* Darker version */
--primary-dark: hsl(240deg 70% 30%);
/* Result: Looks muddy */

Lighten/Darken with OKLCH

/* Base color */
--primary: oklch(0.55 0.20 250);

/* Lighter version - increase lightness */
--primary-light: oklch(0.75 0.20 250);
/* Result: Perfectly lighter, maintains vibrancy */

/* Darker version - decrease lightness */
--primary-dark: oklch(0.35 0.20 250);
/* Result: Perfectly darker, maintains richness */

Specific Advantages of OKLCH

1. Consistent Grayscale

/* HSL grayscale - lightness doesn't match perception */
.gray-hsl { color: hsl(0deg 0% 50%); }

/* OKLCH grayscale - true perceptual middle gray */
.gray-oklch { color: oklch(0.50 0.00 0); }

2. Better Saturation Control

/* HSL - saturation behaves differently at different lightnesses */
.hsl-saturated-light { color: hsl(200deg 100% 80%); } /* Looks pastel */
.hsl-saturated-dark { color: hsl(200deg 100% 20%); }  /* Barely visible */

/* OKLCH - chroma is consistent across lightnesses */
.oklch-saturated-light { color: oklch(0.80 0.15 250); } /* Vibrant */
.oklch-saturated-dark { color: oklch(0.20 0.15 250); }  /* Still saturated */

3. Predictable Color Mixing

When creating intermediate colors or gradients:

/* HSL gradient - uneven brightness progression */
.gradient-hsl {
  background: linear-gradient(
    to right,
    hsl(60deg 100% 50%),   /* Yellow - looks bright */
    hsl(240deg 100% 50%)   /* Blue - looks dark */
  );
  /* Result: Muddy middle, uneven brightness */
}

/* OKLCH gradient - smooth, even progression */
.gradient-oklch {
  background: linear-gradient(
    to right,
    oklch(0.85 0.20 100),  /* Yellow */
    oklch(0.85 0.20 250)   /* Blue */
  );
  /* Result: Smooth, even transition */
}

4. Wider Color Gamut

OKLCH supports Display P3 and other wide-gamut color spaces:

/* HSL limited to sRGB */
.hsl-blue { color: hsl(220deg 100% 50%); }
/* Can't express colors outside sRGB */

/* OKLCH can use full Display P3 gamut */
.oklch-blue { color: oklch(0.60 0.30 250); }
/* Can express much more vivid colors on modern displays */

When HSL Still Makes Sense

There are a few scenarios where HSL might still be preferable:

  1. Legacy browser support - If you need to support very old browsers
  2. Quick prototyping - HSL is more widely known and faster to type
  3. Small projects - If perceptual uniformity isn't critical

However, for any serious design system or production application, OKLCH is the better choice.

Migration Strategy

You don't have to switch everything at once:

Step 1: Use for New Color Variables

:root {
  /* New colors use OKLCH */
  --color-new-primary: oklch(0.60 0.20 250);
  
  /* Legacy colors keep HSL for now */
  --color-old-primary: hsl(220deg 70% 50%);
}

Step 2: Convert Critical Colors

Start with your most important colors - primary brand colors, text, backgrounds:

/* Before */
--color-text: hsl(0deg 0% 10%);

/* After */
--color-text: oklch(0.20 0.00 0);

Step 3: Update Design System

Rebuild your color palettes using OKLCH for perfect consistency:

/* Complete rebrand with OKLCH */
:root {
  /* Primary */
  --primary-50: oklch(0.97 0.08 250);
  --primary-100: oklch(0.93 0.10 250);
  --primary-200: oklch(0.85 0.13 250);
  /* ... rest of palette */
}

Real-World Benefits

Case Study: Dark Mode

With HSL, creating dark mode often requires manually tweaking each color to look right. With OKLCH:

/* Automatic dark mode by just adjusting lightness */
:root {
  --bg: oklch(0.98 0.01 270);
  --text: oklch(0.20 0.02 270);
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: oklch(0.15 0.02 270);   /* Just flip lightness */
    --text: oklch(0.90 0.02 270);  /* Just flip lightness */
  }
}

Case Study: Multi-Color Themes

Creating themes with different accent colors is trivial:

/* Blue theme */
.theme-blue {
  --accent: oklch(0.60 0.20 250);
}

/* Green theme - just change hue */
.theme-green {
  --accent: oklch(0.60 0.20 140);
}

/* All shades automatically consistent! */
--accent-light: oklch(0.75 0.20 var(--accent-hue));
--accent-dark: oklch(0.45 0.20 var(--accent-hue));

Conclusion

OKLCH isn't just a trendy new color space—it's a fundamental improvement over HSL that solves real problems:

✅ Perceptual uniformity = predictable colors
✅ Easier accessibility compliance
✅ Consistent color palettes across all hues
✅ Better dark mode support
✅ Access to wide color gamuts
✅ More intuitive color manipulation

The learning curve is minimal—if you understand HSL, you'll pick up OKLCH in minutes. The benefits, however, are substantial and immediate.

Ready to make the switch? Start with our migration guide or explore our color picker tool to experiment with OKLCH colors.