#3666DC
Closest named color: Royal Blue (#4169E1). oklch(54.6% 0.188 264.3), rgb(54, 102, 220).
Aa
White text reads best on this color (5.13:1).
About this color
#3666DC is a medium-dark, vivid blue. In OKLCH its lightness is 55%, its chroma 0.188 and its hue 264°. Its hue sits on the cool side of the wheel. The nearest named color is Royal Blue (#4169E1), ΔE 0.016 away. White text reads best on it, at 5.13:1.
| Hue family | Blues |
| Lightness | medium-dark (55%) |
| Chroma | vivid (0.188) |
| Temperature | cool |
| Nearest name | Royal Blue (#4169E1) |
| Black text | 4.09:1 |
| White text | 5.13:1 |
Values
| HEX | #3666DC |
| RGB | rgb(54, 102, 220) |
| HSL | hsl(223, 70%, 54%) |
| OKLCH | oklch(54.6% 0.188 264.3) |
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 #3666DC | 5.13:1 | AA | Lc -80.3 | Fine for body text |
| Black text on #3666DC | 4.09:1 | AA large text | Lc 29.2 | Dividers and decoration only |
| #3666DC text on white | 5.13:1 | AA | Lc 74.9 | Content text, not long reading |
| #3666DC text on black | 4.09:1 | AA large text | Lc -26.8 | 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
#F2F6FD
oklch(97.2% 0.01 261.8)
-
Step 100
100
#E2EAFB
oklch(93.6% 0.025 265.6)
-
Step 200
200
#CAD9F9
oklch(88.4% 0.047 265.5)
-
Step 300
300
#A5C0F8
oklch(80.8% 0.085 264.6)
-
Step 400
400
#769EF5
oklch(70.7% 0.135 264.5)
-
Step 500
500
#5383F1
oklch(63.1% 0.173 264.3)
-
Step 600
600 (this color)
#3666DC
oklch(54.6% 0.188 264.3)
-
Step 700
700
#2C57C2
oklch(49.1% 0.175 264.3)
-
Step 800
800
#25489D
oklch(42.8% 0.145 264.3)
-
Step 900
900
#223D7D
oklch(37.7% 0.114 264.4)
-
Step 950
950
#142449
oklch(26.9% 0.072 264.5)
#3666DC 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) | #0076E0 | 0.042 |
| Deuteranopia (no green cones) | #0066DA | 0.026 |
| Tritanopia (no blue cones) | #008397 | 0.149 |
| Achromatopsia (no color) | #6E6E6E | 0.188 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #3666DC
#3666DC
oklch(54.6% 0.188 264.3)
- #8F6A00
#8F6A00
oklch(54.7% 0.112 84.4)
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 #3666DC, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Royal Blue #4169E1 ΔE 0.016
- Neon Blue #4361EE ΔE 0.032
- Cerulean Blue #056EEE ΔE 0.036
- Warm Blue #4B57DB ΔE 0.038
- Azul #1D5DEC ΔE 0.039
- Bright Blue #0165FC ΔE 0.053
- Dark Periwinkle #665FD1 ΔE 0.058
- Iris #6258C4 ΔE 0.066
Use #3666DC 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.