HSL (Hue, Saturation, Lightness) has a problem: its lightness value is not perceptually uniform. A yellow at HSL lightness 50% looks much brighter than a blue at HSL lightness 50%. OKLCH solves this by using a perceptually uniform lightness channel where equal values genuinely look equally bright.
What Is OKLCH?
OKLCH stands for OK Lightness Chroma Hue. It is a cylindrical color space based on the OKLAB perceptual color model. In OKLCH, L (lightness, 0 to 1) corresponds to perceived brightness. C (chroma, 0 to approximately 0.4) corresponds to color intensity. H (hue, 0 to 360) corresponds to the color angle.
Why It Matters for Web Design
When you generate shade scales in HSL by stepping lightness evenly, the results look uneven because HSL lightness is not perceptually linear. In OKLCH, even lightness steps produce even perceived brightness steps. This means shade scales generated in OKLCH look better and more professional.
CSS Support
OKLCH is supported in modern CSS: color: oklch(0.59 0.2 264); Browser support covers Chrome, Firefox, Safari, and Edge. Combined with color-mix(in oklch, ...), you can generate shade variants, tints, and blends that are perceptually accurate.
Practical Adoption
For most projects, you do not need to switch your entire palette to OKLCH. Continue using hex values from PaletteRx for your base colors. Use OKLCH for shade generation and dynamic color manipulation where perceptual accuracy matters.