#3F66B4
Closest named color: French Blue (#436BAD). oklch(52.1% 0.131 262.7), rgb(63, 102, 180).
Aa
White text reads best on this color (5.56:1).
About this color
#3F66B4 is a medium-dark, moderately saturated blue. In OKLCH its lightness is 52%, its chroma 0.131 and its hue 263°. Its hue sits on the cool side of the wheel. The nearest named color is French Blue (#436BAD), ΔE 0.020 away. White text reads best on it, at 5.56:1.
| Hue family | Blues |
| Lightness | medium-dark (52%) |
| Chroma | moderately saturated (0.131) |
| Temperature | cool |
| Nearest name | French Blue (#436BAD) |
| Black text | 3.77:1 |
| White text | 5.56:1 |
Values
| HEX | #3F66B4 |
| RGB | rgb(63, 102, 180) |
| HSL | hsl(220, 48%, 48%) |
| OKLCH | oklch(52.1% 0.131 262.7) |
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 #3F66B4 | 5.56:1 | AA | Lc -82.9 | Fine for body text |
| Black text on #3F66B4 | 3.77:1 | AA large text | Lc 26.5 | Dividers and decoration only |
| #3F66B4 text on white | 5.56:1 | AA | Lc 77.6 | Fine for body text |
| #3F66B4 text on black | 3.77:1 | AA large text | Lc -24.2 | 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 700.
-
Step 50
50
#F2F6FB
oklch(97.2% 0.008 253.9)
-
Step 100
100
#E3EAF7
oklch(93.6% 0.019 263)
-
Step 200
200
#CDDAF1
oklch(88.6% 0.035 262)
-
Step 300
300
#ABC1EA
oklch(80.8% 0.063 262.8)
-
Step 400
400
#7FA0E0
oklch(70.6% 0.101 263.1)
-
Step 500
500
#5E87D8
oklch(63% 0.131 262.9)
-
Step 600
600
#4570C5
oklch(55.7% 0.141 262.5)
-
Step 700
700 (this color)
#3F66B4
oklch(52.1% 0.131 262.7)
-
Step 800
800
#2E4C8A
oklch(42.7% 0.109 263.1)
-
Step 900
900
#29406E
oklch(37.7% 0.084 262.9)
-
Step 950
950
#182641
oklch(27.1% 0.054 262.5)
#3F66B4 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) | #426EB7 | 0.023 |
| Deuteranopia (no green cones) | #2F63B2 | 0.019 |
| Tritanopia (no blue cones) | #007884 | 0.109 |
| Achromatopsia (no color) | #686868 | 0.131 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #3F66B4
#3F66B4
oklch(52.1% 0.131 262.7)
- #876200
#876200
oklch(52.1% 0.107 82.7)
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 #3F66B4, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- French Blue #436BAD ΔE 0.020
- Mid Blue #276AB3 ΔE 0.022
- Flat Blue #3C73A8 ΔE 0.045
- Windows Blue #3778BF ΔE 0.049
- Muted Blue #3B719F ΔE 0.051
- Dusky Blue #475F94 ΔE 0.051
- Denim Blue #3B5B92 ΔE 0.059
- Nice Blue #107AB0 ΔE 0.061
Use #3F66B4 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.