#3F66EB
Closest named color: Neon Blue (#4361EE). oklch(56.1% 0.205 267), rgb(63, 102, 235).
Aa
White text reads best on this color (4.87:1).
About this color
#3F66EB is a medium-dark, vivid blue. In OKLCH its lightness is 56%, its chroma 0.205 and its hue 267°. Its hue sits on the cool side of the wheel. The nearest named color is Neon Blue (#4361EE), ΔE 0.012 away. White text reads best on it, at 4.87:1.
| Hue family | Blues |
| Lightness | medium-dark (56%) |
| Chroma | vivid (0.205) |
| Temperature | cool |
| Nearest name | Neon Blue (#4361EE) |
| Black text | 4.31:1 |
| White text | 4.87:1 |
Values
| HEX | #3F66EB |
| RGB | rgb(63, 102, 235) |
| HSL | hsl(226, 81%, 58%) |
| OKLCH | oklch(56.1% 0.205 267) |
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 #3F66EB | 4.87:1 | AA | Lc -78.7 | Fine for body text |
| Black text on #3F66EB | 4.31:1 | AA large text | Lc 30.9 | Non-text elements, placeholder text |
| #3F66EB text on white | 4.87:1 | AA | Lc 73.2 | Content text, not long reading |
| #3F66EB text on black | 4.31:1 | 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
#F2F5FE
oklch(97% 0.012 271.3)
-
Step 100
100
#E2EAFC
oklch(93.6% 0.026 266.6)
-
Step 200
200
#CAD9FC
oklch(88.5% 0.051 267)
-
Step 300
300
#A6BFFD
oklch(80.8% 0.092 267.4)
-
Step 400
400
#779CFC
oklch(70.8% 0.147 266.7)
-
Step 500
500
#567FFA
oklch(63.1% 0.189 267)
-
Step 600
600 (this color)
#3F66EB
oklch(56.1% 0.205 267)
-
Step 700
700
#3152CB
oklch(49.1% 0.191 267.1)
-
Step 800
800
#2844A4
oklch(42.6% 0.159 267)
-
Step 900
900
#243B82
oklch(37.7% 0.123 266.8)
-
Step 950
950
#15234C
oklch(27% 0.078 266.9)
#3F66EB 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) | #0079F0 | 0.049 |
| Deuteranopia (no green cones) | #0069E8 | 0.033 |
| Tritanopia (no blue cones) | #00879F | 0.162 |
| Achromatopsia (no color) | #717171 | 0.206 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #3F66EB
#3F66EB
oklch(56.1% 0.205 267)
- #926F00
#926F00
oklch(56.1% 0.115 86.6)
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 #3F66EB, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Neon Blue #4361EE ΔE 0.012
- Royal Blue #4169E1 ΔE 0.017
- Cerulean Blue #056EEE ΔE 0.032
- Azul #1D5DEC ΔE 0.037
- Bright Blue #0165FC ΔE 0.041
- Warm Blue #4B57DB ΔE 0.041
- Clear Blue #247AFD ΔE 0.053
- Dark Periwinkle #665FD1 ΔE 0.061
Use #3F66EB 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.