#666FA3
Closest named color: Dull Blue (#49759C). oklch(55.6% 0.082 275.9), rgb(102, 111, 163).
Aa
White text reads best on this color (4.80:1).
About this color
#666FA3 is a medium-dark, moderately saturated blue. In OKLCH its lightness is 56%, its chroma 0.082 and its hue 276°. Its hue sits on the cool side of the wheel. The nearest named color is Dull Blue (#49759C), ΔE 0.042 away. White text reads best on it, at 4.80:1.
| Hue family | Blues |
| Lightness | medium-dark (56%) |
| Chroma | moderately saturated (0.082) |
| Temperature | cool |
| Nearest name | Dull Blue (#49759C) |
| Black text | 4.36:1 |
| White text | 4.80:1 |
Values
| HEX | #666FA3 |
| RGB | rgb(102, 111, 163) |
| HSL | hsl(231, 25%, 52%) |
| OKLCH | oklch(55.6% 0.082 275.9) |
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 #666FA3 | 4.80:1 | AA | Lc -78.7 | Fine for body text |
| Black text on #666FA3 | 4.36:1 | AA large text | Lc 30.8 | Non-text elements, placeholder text |
| #666FA3 text on white | 4.80:1 | AA | Lc 73.3 | Content text, not long reading |
| #666FA3 text on black | 4.36:1 | AA large text | Lc -28.4 | 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
#F4F5F9
oklch(97.1% 0.005 275)
-
Step 100
100
#E8E9F1
oklch(93.6% 0.011 280.5)
-
Step 200
200
#D5D8E7
oklch(88.4% 0.021 276.9)
-
Step 300
300
#BABFD9
oklch(80.9% 0.037 276.9)
-
Step 400
400
#969EC6
oklch(70.7% 0.059 276)
-
Step 500
500
#7D86B7
oklch(63.2% 0.075 276)
-
Step 600
600 (this color)
#666FA3
oklch(55.6% 0.082 275.9)
-
Step 700
700
#555D8C
oklch(49.2% 0.076 275.9)
-
Step 800
800
#454C71
oklch(42.7% 0.062 275.3)
-
Step 900
900
#3A3F5C
oklch(37.6% 0.05 276.2)
-
Step 950
950
#222536
oklch(27% 0.032 276.3)
#666FA3 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) | #5E75A5 | 0.018 |
| Deuteranopia (no green cones) | #5A70A2 | 0.016 |
| Tritanopia (no blue cones) | #547982 | 0.072 |
| Achromatopsia (no color) | #727272 | 0.082 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #666FA3
#666FA3
oklch(55.6% 0.082 275.9)
- #817337
#817337
oklch(55.5% 0.082 96.4)
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 #666FA3, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Dull Blue #49759C ΔE 0.042
- Stormy Blue #507B9C ΔE 0.046
- Flat Blue #3C73A8 ΔE 0.048
- French Blue #436BAD ΔE 0.049
- Metallic Blue #4F738E ΔE 0.050
- Dark Lavender #856798 ΔE 0.051
- Muted Blue #3B719F ΔE 0.051
- Cerulean #457B9D ΔE 0.052
Use #666FA3 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.