#3666EF
Closest named color: Neon Blue (#4361EE). oklch(56% 0.213 265.3), rgb(54, 102, 239).
Aa
White text reads best on this color (4.87:1).
About this color
#3666EF is a medium-dark, vivid blue. In OKLCH its lightness is 56%, its chroma 0.213 and its hue 265°. Its hue sits on the cool side of the wheel. The nearest named color is Neon Blue (#4361EE), ΔE 0.015 away. White text reads best on it, at 4.87:1.
| Hue family | Blues |
| Lightness | medium-dark (56%) |
| Chroma | vivid (0.213) |
| Temperature | cool |
| Nearest name | Neon Blue (#4361EE) |
| Black text | 4.30:1 |
| White text | 4.87:1 |
Values
| HEX | #3666EF |
| RGB | rgb(54, 102, 239) |
| HSL | hsl(224, 85%, 57%) |
| OKLCH | oklch(56% 0.213 265.3) |
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 #3666EF | 4.87:1 | AA | Lc -78.6 | Fine for body text |
| Black text on #3666EF | 4.30:1 | AA large text | Lc 30.9 | Non-text elements, placeholder text |
| #3666EF text on white | 4.87:1 | AA | Lc 73.2 | Content text, not long reading |
| #3666EF text on black | 4.30:1 | 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
#F1F6FE
oklch(97.2% 0.012 259.8)
-
Step 100
100
#E1EAFD
oklch(93.6% 0.028 265.4)
-
Step 200
200
#C8D9FD
oklch(88.4% 0.053 265.3)
-
Step 300
300
#A3C0FF
oklch(80.9% 0.095 265.2)
-
Step 400
400
#729CFF
oklch(70.6% 0.153 265.4)
-
Step 500
500
#4F7FFE
oklch(63% 0.196 265.5)
-
Step 600
600 (this color)
#3666EF
oklch(56% 0.213 265.3)
-
Step 700
700
#2852CF
oklch(49.1% 0.199 265.3)
-
Step 800
800
#2244A7
oklch(42.7% 0.164 265.4)
-
Step 900
900
#203B84
oklch(37.7% 0.127 265.4)
-
Step 950
950
#13234D
oklch(26.9% 0.08 265.6)
#3666EF 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) | #007AF4 | 0.048 |
| Deuteranopia (no green cones) | #0069EC | 0.025 |
| Tritanopia (no blue cones) | #0089A1 | 0.167 |
| Achromatopsia (no color) | #717171 | 0.213 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #3666EF
#3666EF
oklch(56% 0.213 265.3)
- #936E00
#936E00
oklch(56% 0.115 85.2)
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 #3666EF, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Neon Blue #4361EE ΔE 0.015
- Royal Blue #4169E1 ΔE 0.025
- Cerulean Blue #056EEE ΔE 0.026
- Azul #1D5DEC ΔE 0.031
- Bright Blue #0165FC ΔE 0.031
- Warm Blue #4B57DB ΔE 0.047
- Clear Blue #247AFD ΔE 0.050
- Electric Blue #0652FF ΔE 0.059
Use #3666EF 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.