#663B91
Closest named color: Rebecca Purple (#663399). oklch(44.6% 0.139 304.4), rgb(102, 59, 145).
Aa
White text reads best on this color (8.07:1).
About this color
#663B91 is a dark, moderately saturated purple. In OKLCH its lightness is 45%, its chroma 0.139 and its hue 304°. Its hue sits between the warm and cool halves of the wheel. The nearest named color is Rebecca Purple (#663399), ΔE 0.023 away. White text reads best on it, at 8.07:1.
| Hue family | Purples |
| Lightness | dark (45%) |
| Chroma | moderately saturated (0.139) |
| Temperature | in between |
| Nearest name | Rebecca Purple (#663399) |
| Black text | 2.59:1 |
| White text | 8.07:1 |
Values
| HEX | #663B91 |
| RGB | rgb(102, 59, 145) |
| HSL | hsl(270, 42%, 40%) |
| OKLCH | oklch(44.6% 0.139 304.4) |
Contrast
WCAG 2 contrast ratios are the conformance target: AA needs 4.5:1 for body text and 3:1 for large text, AAA needs 7:1. APCA Lc values are supplementary guidance from the WCAG 3 drafts.
| Pair | WCAG 2 | Result | APCA | APCA guidance |
|---|---|---|---|---|
| White text on #663B91 | 8.07:1 | AAA | Lc -92.3 | Preferred for body text |
| Black text on #663B91 | 2.59:1 | Fails | Lc 16.4 | Dividers and decoration only |
| #663B91 text on white | 8.07:1 | AAA | Lc 87.6 | Fine for body text |
| #663B91 text on black | 2.59:1 | Fails | Lc -14.5 | Not readable |
Tints and shades
A 50–950 scale built in OKLCH: the hue is held, lightness follows a Tailwind v4-like curve, and every step is kept inside the sRGB gamut. This color sits at step 800.
-
Step 50
50
#F7F4FC
oklch(97.2% 0.011 303.1)
-
Step 100
100
#EDE6F7
oklch(93.5% 0.024 304.5)
-
Step 200
200
#E0D2F2
oklch(88.5% 0.046 305.2)
-
Step 300
300
#CCB4EC
oklch(80.9% 0.082 304.2)
-
Step 400
400
#B38BE2
oklch(70.8% 0.13 304.4)
-
Step 500
500
#A06BD9
oklch(63% 0.166 304.3)
-
Step 600
600
#8C50C7
oklch(55.7% 0.181 304.4)
-
Step 700
700
#7740AC
oklch(49.2% 0.168 304.4)
-
Step 800
800 (this color)
#663B91
oklch(44.6% 0.139 304.4)
-
Step 900
900
#4F2F6F
oklch(37.6% 0.109 304.8)
-
Step 950
950
#2E1C41
oklch(26.9% 0.069 304.6)
#663B91 with color blindness
Simulated with the Machado et al. (2009) model. ΔE is how far the color moves: below about 0.02 you would not notice a change.
| Vision | Seen as | Shift (ΔE) |
|---|---|---|
| Protanopia (no red cones) | #164F94 | 0.111 |
| Deuteranopia (no green cones) | #29508F | 0.099 |
| Tritanopia (no blue cones) | #5E4C60 | 0.102 |
| Achromatopsia (no color) | #505050 | 0.140 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #663B91
#663B91
oklch(44.6% 0.139 304.4)
- #475E00
#475E00
oklch(44.7% 0.112 124.5)
Analogous
Neighbouring hues, 30° either side.
Split complementary
The two hues beside the complement (150° and 210°).
Triadic
Three hues spaced 120° apart.
Palettes with this color
Curated palettes that contain a color within ΔE 0.04 (OKLab) of #663B91, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Rebecca Purple #663399 ΔE 0.023
- Dark Slate Blue #483D8B ΔE 0.055
- Blueberry #464196 ΔE 0.057
- Twilight #4E518B ΔE 0.068
- Light Eggplant #894585 ΔE 0.079
- Dusk #4E5481 ΔE 0.082
- Bluey Purple #6241C7 ΔE 0.087
- Grape #7209B7 ΔE 0.089
Use #663B91 in your product
Turn it into light and dark UI roles checked for contrast, then export to Tailwind v4, shadcn/ui, CSS or design tokens.