#666E99
Closest named color: Dull Blue (#49759C). oklch(54.9% 0.068 275.8), rgb(102, 110, 153).
Aa
White text reads best on this color (4.93:1).
About this color
#666E99 is a medium-dark, muted blue. In OKLCH its lightness is 55%, its chroma 0.068 and its hue 276°. Its hue sits on the cool side of the wheel. The nearest named color is Dull Blue (#49759C), ΔE 0.038 away. White text reads best on it, at 4.93:1.
| Hue family | Blues |
| Lightness | medium-dark (55%) |
| Chroma | muted (0.068) |
| Temperature | cool |
| Nearest name | Dull Blue (#49759C) |
| Black text | 4.25:1 |
| White text | 4.93:1 |
Values
| HEX | #666E99 |
| RGB | rgb(102, 110, 153) |
| HSL | hsl(231, 20%, 50%) |
| OKLCH | oklch(54.9% 0.068 275.8) |
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 #666E99 | 4.93:1 | AA | Lc -79.6 | Fine for body text |
| Black text on #666E99 | 4.25:1 | AA large text | Lc 29.9 | Dividers and decoration only |
| #666E99 text on white | 4.93:1 | AA | Lc 74.2 | Content text, not long reading |
| #666E99 text on black | 4.25:1 | AA large text | Lc -27.6 | 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
#D6D8E5
oklch(88.5% 0.018 279)
-
Step 300
300
#BBBFD5
oklch(80.8% 0.031 277.5)
-
Step 400
400
#989FC0
oklch(70.8% 0.049 275.7)
-
Step 500
500
#7F87B0
oklch(63.2% 0.062 275.9)
-
Step 600
600 (this color)
#666E99
oklch(54.9% 0.068 275.8)
-
Step 700
700
#575E85
oklch(49.2% 0.063 276)
-
Step 800
800
#474D6C
oklch(42.8% 0.052 275.5)
-
Step 900
900
#3B4057
oklch(37.7% 0.04 274.8)
-
Step 950
950
#232533
oklch(26.9% 0.026 278.2)
#666E99 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) | #61729B | 0.012 |
| Deuteranopia (no green cones) | #5D6E98 | 0.013 |
| Tritanopia (no blue cones) | #58767D | 0.060 |
| Achromatopsia (no color) | #707070 | 0.068 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #666E99
#666E99
oklch(54.9% 0.068 275.8)
- #7D7142
#7D7142
oklch(54.8% 0.067 95.5)
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 #666E99, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Dull Blue #49759C ΔE 0.038
- Metallic Blue #4F738E ΔE 0.039
- Stormy Blue #507B9C ΔE 0.043
- Grey Purple #826D8C ΔE 0.046
- Cerulean #457B9D ΔE 0.050
- Dark Lavender #856798 ΔE 0.050
- Muted Blue #3B719F ΔE 0.050
- Flat Blue #3C73A8 ΔE 0.051
Use #666E99 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.