HEX to HSL: #663399

Also known as: CSS rebeccapurple

#663399 → hsl(270 50% 40%)

Values are shown at full precision, so converting back gives exactly #663399. The rounded form is what you normally paste into CSS.

Step-by-step math

Every number below is computed from the input, nothing is looked up.

1. RGB ÷ 255
```
R = 0.4000
G = 0.2000
B = 0.6000
```

2. max, min, Δ

max = 0.6000
min = 0.2000
Δ = max − min = 0.4000

3. L
```
L = (max + min) / 2 = 0.4000 = 40.00%
```

4. S

S = Δ / (1 − |2L − 1|) = 0.5000 = 50.00%

5. H

max is B → H = 60° × ((R − G) / Δ + 4) = 60° × ((0.4000 − 0.2000) / 0.4000 + 4) = 270.00°

6. HSL
```
hsl(270.00 50.00% 40.00%)
```

All formats

HEX: #663399
RGB: rgb(102 51 153)
RGB (legacy): rgb(102, 51, 153)
HSL: hsl(270.00 50.00% 40.00%) → hsl(270 50% 40%)
HWB: hwb(270 20% 40%)
OKLCH: oklch(0.440 0.160 303.4) · oklch(44.0% 0.160 303.4)
OKLab: oklab(0.440 0.088 -0.134)
Lab (D50): lab(32.39 38.42 -47.69)
LCH (D50): lch(32.39 61.24 308.86)
Display P3: color(display-p3 0.3737 0.2103 0.5791)
Linear sRGB: color(srgb-linear 0.1329 0.0331 0.3185)

Gamut: sRGB and Display P3

#663399 is a hex color, so it sits inside sRGB and therefore inside Display P3. At this lightness and hue, sRGB reaches chroma 0.231 and Display P3 reaches 0.241; this color uses 69% of the sRGB chroma available.

CSS snippets

.element {
  color: #663399;
  color: rgb(102 51 153);
  color: hsl(270 50% 40%);
  color: oklch(0.440 0.160 303.4);
}

/* Tailwind CSS v4 */
@theme {
  --color-brand: oklch(0.440 0.160 303.4);
}
/* arbitrary values */
class="text-[#663399] bg-[oklch(0.440_0.160_303.4)]"

/* wide-gamut screens */
@media (color-gamut: p3) {
  .element { color: color(display-p3 0.3737 0.2103 0.5791); }
}

/* relative color syntax: 10% darker */
.element-dark { color: oklch(from #663399 calc(l - 0.1) c h); }

Nearby colors

Closest colors in the Tailwind and CSS named palettes (OKLab distance).

Lighter and darker, same hue and chroma

#7745AC · oklch(0.500 0.160 303.4) · ΔL +0.06
#552086 · oklch(0.380 0.160 303.4) · ΔL −0.06

Open in the studio

Open in the OKLCH picker Check contrast on white

Other converters for this color

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Guides: What is OKLCH?