#666E9D
Closest named color: Dull Blue (#49759C). oklch(55.1% 0.074 276.3), rgb(102, 110, 157).
Aa
White text reads best on this color (4.90:1).
About this color
#666E9D is a medium-dark, moderately saturated blue. In OKLCH its lightness is 55%, its chroma 0.074 and its hue 276°. Its hue sits on the cool side of the wheel. The nearest named color is Dull Blue (#49759C), ΔE 0.039 away. White text reads best on it, at 4.90:1.
| Hue family | Blues |
| Lightness | medium-dark (55%) |
| Chroma | moderately saturated (0.074) |
| Temperature | cool |
| Nearest name | Dull Blue (#49759C) |
| Black text | 4.28:1 |
| White text | 4.90:1 |
Values
| HEX | #666E9D |
| RGB | rgb(102, 110, 157) |
| HSL | hsl(231, 22%, 51%) |
| OKLCH | oklch(55.1% 0.074 276.3) |
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 #666E9D | 4.90:1 | AA | Lc -79.4 | Fine for body text |
| Black text on #666E9D | 4.28:1 | AA large text | Lc 30.1 | Non-text elements, placeholder text |
| #666E9D text on white | 4.90:1 | AA | Lc 73.9 | Content text, not long reading |
| #666E9D text on black | 4.28:1 | AA large text | Lc -27.8 | Dividers and decoration only |
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 600.
-
Step 50
50
#F4F5F8
oklch(97% 0.004 271.4)
-
Step 100
100
#E8E9F0
oklch(93.5% 0.009 279.7)
-
Step 200
200
#D5D8E6
oklch(88.4% 0.019 276.3)
-
Step 300
300
#BABFD7
oklch(80.8% 0.034 276.3)
-
Step 400
400
#979EC2
oklch(70.6% 0.053 276.3)
-
Step 500
500
#7E86B3
oklch(63.1% 0.068 276.4)
-
Step 600
600 (this color)
#666E9D
oklch(55.1% 0.074 276.3)
-
Step 700
700
#565D88
oklch(49.1% 0.069 276.4)
-
Step 800
800
#464C6E
oklch(42.6% 0.057 276)
-
Step 900
900
#3B4059
oklch(37.8% 0.043 275.4)
-
Step 950
950
#232534
oklch(26.9% 0.028 278.4)
#666E9D 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) | #5F739F | 0.016 |
| Deuteranopia (no green cones) | #5C6F9C | 0.014 |
| Tritanopia (no blue cones) | #57777F | 0.065 |
| Achromatopsia (no color) | #717171 | 0.074 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #666E9D
#666E9D
oklch(55.1% 0.074 276.3)
- #7E723D
#7E723D
oklch(55.1% 0.074 96.9)
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 #666E9D, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Dull Blue #49759C ΔE 0.039
- Metallic Blue #4F738E ΔE 0.044
- Stormy Blue #507B9C ΔE 0.044
- Grey Purple #826D8C ΔE 0.049
- Dark Lavender #856798 ΔE 0.049
- Flat Blue #3C73A8 ΔE 0.050
- Muted Blue #3B719F ΔE 0.050
- Cerulean #457B9D ΔE 0.051
Use #666E9D 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.