#3666E6
Closest named color: Royal Blue (#4169E1). oklch(55.3% 0.201 264.9), rgb(54, 102, 230).
Aa
White text reads best on this color (4.99:1).
About this color
#3666E6 is a medium-dark, vivid blue. In OKLCH its lightness is 55%, its chroma 0.201 and its hue 265°. 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 4.99:1.
| Hue family | Blues |
| Lightness | medium-dark (55%) |
| Chroma | vivid (0.201) |
| Temperature | cool |
| Nearest name | Royal Blue (#4169E1) |
| Black text | 4.20:1 |
| White text | 4.99:1 |
Values
| HEX | #3666E6 |
| RGB | rgb(54, 102, 230) |
| HSL | hsl(224, 78%, 56%) |
| OKLCH | oklch(55.3% 0.201 264.9) |
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 #3666E6 | 4.99:1 | AA | Lc -79.4 | Fine for body text |
| Black text on #3666E6 | 4.20:1 | AA large text | Lc 30.1 | Non-text elements, placeholder text |
| #3666E6 text on white | 4.99:1 | AA | Lc 74.0 | Content text, not long reading |
| #3666E6 text on black | 4.20:1 | AA large text | Lc -27.7 | 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
#F1F6FE
oklch(97.2% 0.012 259.8)
-
Step 100
100
#E1EAFC
oklch(93.6% 0.026 264.4)
-
Step 200
200
#C9D9FB
oklch(88.4% 0.05 265.4)
-
Step 300
300
#A4C0FC
oklch(80.9% 0.091 265)
-
Step 400
400
#749DFB
oklch(70.7% 0.145 265.1)
-
Step 500
500
#5181F8
oklch(63.1% 0.185 265)
-
Step 600
600 (this color)
#3666E6
oklch(55.3% 0.201 264.9)
-
Step 700
700
#2A54C9
oklch(49% 0.188 265)
-
Step 800
800
#2346A2
oklch(42.7% 0.155 264.8)
-
Step 900
900
#213C81
oklch(37.7% 0.121 265)
-
Step 950
950
#13244B
oklch(27% 0.076 264.2)
#3666E6 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) | #0078EA | 0.045 |
| Deuteranopia (no green cones) | #0068E3 | 0.025 |
| Tritanopia (no blue cones) | #00869C | 0.158 |
| Achromatopsia (no color) | #6F6F6F | 0.202 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #3666E6
#3666E6
oklch(55.3% 0.201 264.9)
- #916C00
#916C00
oklch(55.4% 0.113 84.8)
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 #3666E6, 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 0.020
- Cerulean Blue #056EEE ΔE 0.028
- Azul #1D5DEC ΔE 0.031
- Warm Blue #4B57DB ΔE 0.040
- Bright Blue #0165FC ΔE 0.040
- Clear Blue #247AFD ΔE 0.057
- Dark Periwinkle #665FD1 ΔE 0.063
Use #3666E6 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.