#666C91
Closest named color: Metallic Blue (#4F738E). oklch(54.1% 0.058 277.1), rgb(102, 108, 145).
Aa
White text reads best on this color (5.09:1).
About this color
#666C91 is a medium-dark, muted blue. In OKLCH its lightness is 54%, its chroma 0.058 and its hue 277°. Its hue sits on the cool side of the wheel. The nearest named color is Metallic Blue (#4F738E), ΔE 0.036 away. White text reads best on it, at 5.09:1.
| Hue family | Blues |
| Lightness | medium-dark (54%) |
| Chroma | muted (0.058) |
| Temperature | cool |
| Nearest name | Metallic Blue (#4F738E) |
| Black text | 4.11:1 |
| White text | 5.09:1 |
Values
| HEX | #666C91 |
| RGB | rgb(102, 108, 145) |
| HSL | hsl(232, 17%, 48%) |
| OKLCH | oklch(54.1% 0.058 277.1) |
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 #666C91 | 5.09:1 | AA | Lc -80.6 | Fine for body text |
| Black text on #666C91 | 4.11:1 | AA large text | Lc 28.9 | Dividers and decoration only |
| #666C91 text on white | 5.09:1 | AA | Lc 75.2 | Fine for body text |
| #666C91 text on black | 4.11:1 | AA large text | Lc -26.5 | 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
#F5F5F8
oklch(97.1% 0.004 286.3)
-
Step 100
100
#E8E9EF
oklch(93.5% 0.008 278.6)
-
Step 200
200
#D6D8E3
oklch(88.4% 0.015 277.8)
-
Step 300
300
#BCBFD2
oklch(80.8% 0.027 278.6)
-
Step 400
400
#9A9FBB
oklch(70.8% 0.041 277.3)
-
Step 500
500
#8187AA
oklch(63.1% 0.053 277.2)
-
Step 600
600 (this color)
#666C91
oklch(54.1% 0.058 277.1)
-
Step 700
700
#595E80
oklch(49.1% 0.055 277.7)
-
Step 800
800
#494D68
oklch(42.8% 0.045 277.8)
-
Step 900
900
#3D4054
oklch(37.7% 0.034 278)
-
Step 950
950
#242631
oklch(27.1% 0.021 276.9)
#666C91 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) | #617093 | 0.012 |
| Deuteranopia (no green cones) | #5F6D90 | 0.010 |
| Tritanopia (no blue cones) | #5B7379 | 0.052 |
| Achromatopsia (no color) | #6E6E6E | 0.058 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #666C91
#666C91
oklch(54.1% 0.058 277.1)
- #786F47
#786F47
oklch(54% 0.058 97)
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 #666C91, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Metallic Blue #4F738E ΔE 0.036
- Dull Blue #49759C ΔE 0.041
- Grey Purple #826D8C ΔE 0.044
- Stormy Blue #507B9C ΔE 0.047
- Battleship Gray #6C757D ΔE 0.048
- Grey Blue #647D8E ΔE 0.051
- Dark Lavender #856798 ΔE 0.052
- Muted Blue #3B719F ΔE 0.053
Use #666C91 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.