#066FD9
Closest named color: Cerulean Blue (#056EEE). oklch(55.2% 0.183 255.5), rgb(6, 111, 217).
Aa
White text reads best on this color (4.90:1).
About this color
#066FD9 is a medium-dark, vivid blue. In OKLCH its lightness is 55%, its chroma 0.183 and its hue 256°. Its hue sits on the cool side of the wheel. The nearest named color is Cerulean Blue (#056EEE), ΔE 0.032 away. White text reads best on it, at 4.90:1.
| Hue family | Blues |
| Lightness | medium-dark (55%) |
| Chroma | vivid (0.183) |
| Temperature | cool |
| Nearest name | Cerulean Blue (#056EEE) |
| Black text | 4.28:1 |
| White text | 4.90:1 |
Values
| HEX | #066FD9 |
| RGB | rgb(6, 111, 217) |
| HSL | hsl(210, 95%, 44%) |
| OKLCH | oklch(55.2% 0.183 255.5) |
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 #066FD9 | 4.90:1 | AA | Lc -78.6 | Fine for body text |
| Black text on #066FD9 | 4.28:1 | AA large text | Lc 30.9 | Non-text elements, placeholder text |
| #066FD9 text on white | 4.90:1 | AA | Lc 73.2 | Content text, not long reading |
| #066FD9 text on black | 4.28:1 | AA large text | Lc -28.5 | 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
#F1F6FD
oklch(97.1% 0.011 256.7)
-
Step 100
100
#E0EBFA
oklch(93.6% 0.024 256.1)
-
Step 200
200
#C6DBF8
oklch(88.5% 0.046 256.5)
-
Step 300
300
#9EC3F6
oklch(80.9% 0.083 256.5)
-
Step 400
400
#66A3F1
oklch(70.7% 0.131 255.2)
-
Step 500
500
#3989EC
oklch(63.1% 0.168 255.6)
-
Step 600
600 (this color)
#066FD9
oklch(55.2% 0.183 255.5)
-
Step 700
700
#005EBB
oklch(49.1% 0.165 255.5)
-
Step 800
800
#044D99
oklch(42.7% 0.14 255.4)
-
Step 900
900
#11417A
oklch(37.8% 0.109 255.5)
-
Step 950
950
#0C2647
oklch(26.9% 0.069 255.8)
#066FD9 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) | #2C7ADD | 0.036 |
| Deuteranopia (no green cones) | #0069D7 | 0.016 |
| Tritanopia (no blue cones) | #008999 | 0.137 |
| Achromatopsia (no color) | #717171 | 0.183 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #066FD9
#066FD9
oklch(55.2% 0.183 255.5)
- #996700
#996700
oklch(55.3% 0.116 75.6)
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 #066FD9, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Cerulean Blue #056EEE ΔE 0.032
- Royal Blue #4169E1 ΔE 0.036
- Azul #1D5DEC ΔE 0.053
- Windows Blue #3778BF ΔE 0.056
- Neon Blue #4361EE ΔE 0.056
- Mid Blue #276AB3 ΔE 0.059
- Bright Blue #0165FC ΔE 0.059
- Clear Blue #247AFD ΔE 0.062
Use #066FD9 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.