#3F428B
Closest named color: Dark Slate Blue (#483D8B). oklch(41.7% 0.119 278.1), rgb(63, 66, 139).
Aa
White text reads best on this color (8.88:1).
About this color
#3F428B is a dark, moderately saturated blue. In OKLCH its lightness is 42%, its chroma 0.119 and its hue 278°. Its hue sits on the cool side of the wheel. The nearest named color is Dark Slate Blue (#483D8B), ΔE 0.018 away. White text reads best on it, at 8.88:1.
| Hue family | Blues |
| Lightness | dark (42%) |
| Chroma | moderately saturated (0.119) |
| Temperature | cool |
| Nearest name | Dark Slate Blue (#483D8B) |
| Black text | 2.36:1 |
| White text | 8.88:1 |
Values
| HEX | #3F428B |
| RGB | rgb(63, 66, 139) |
| HSL | hsl(238, 38%, 40%) |
| OKLCH | oklch(41.7% 0.119 278.1) |
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 #3F428B | 8.88:1 | AAA | Lc -94.6 | Preferred for body text |
| Black text on #3F428B | 2.36:1 | Fails | Lc 13.8 | Not readable |
| #3F428B text on white | 8.88:1 | AAA | Lc 90.1 | Preferred for body text |
| #3F428B text on black | 2.36:1 | Fails | Lc -12.1 | Not readable |
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 800.
-
Step 50
50
#F4F5FC
oklch(97.1% 0.009 279.7)
-
Step 100
100
#E6E9F8
oklch(93.6% 0.02 276.9)
-
Step 200
200
#D3D7F3
oklch(88.5% 0.039 279.1)
-
Step 300
300
#B6BDEE
oklch(81% 0.07 278.4)
-
Step 400
400
#9199E5
oklch(70.7% 0.111 278.5)
-
Step 500
500
#777EDD
oklch(63% 0.142 278.3)
-
Step 600
600
#6165CB
oklch(55.5% 0.155 278.4)
-
Step 700
700
#5054B0
oklch(49.2% 0.144 277.8)
-
Step 800
800 (this color)
#3F428B
oklch(41.7% 0.119 278.1)
-
Step 900
900
#373B72
oklch(37.8% 0.093 277.8)
-
Step 950
950
#202343
oklch(27.1% 0.059 277.6)
#3F428B 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) | #1D4D8E | 0.044 |
| Deuteranopia (no green cones) | #134789 | 0.047 |
| Tritanopia (no blue cones) | #1D5260 | 0.103 |
| Achromatopsia (no color) | #4A4A4A | 0.119 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #3F428B
#3F428B
oklch(41.7% 0.119 278.1)
- #594C00
#594C00
oklch(41.7% 0.086 97.9)
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 #3F428B, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Dark Slate Blue #483D8B ΔE 0.018
- Blueberry #464196 ΔE 0.021
- Cobalt #1E488F ΔE 0.039
- Twilight #4E518B ΔE 0.050
- Dusk Blue #26538D ΔE 0.051
- Light Navy #155084 ΔE 0.057
- Twilight Blue #0A437A ΔE 0.062
- Dusk #4E5481 ΔE 0.063
Use #3F428B 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.