#3F437B
Closest named color: Dark Slate Blue (#483D8B). oklch(40.8% 0.093 278.3), rgb(63, 67, 123).
Aa
White text reads best on this color (9.12:1).
About this color
#3F437B is a dark, moderately saturated blue. In OKLCH its lightness is 41%, its chroma 0.093 and its hue 278°. Its hue sits on the cool side of the wheel. The nearest named color is Dark Slate Blue (#483D8B), ΔE 0.036 away. White text reads best on it, at 9.12:1.
| Hue family | Blues |
| Lightness | dark (41%) |
| Chroma | moderately saturated (0.093) |
| Temperature | cool |
| Nearest name | Dark Slate Blue (#483D8B) |
| Black text | 2.30:1 |
| White text | 9.12:1 |
Values
| HEX | #3F437B |
| RGB | rgb(63, 67, 123) |
| HSL | hsl(236, 32%, 36%) |
| OKLCH | oklch(40.8% 0.093 278.3) |
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 #3F437B | 9.12:1 | AAA | Lc -95.3 | Preferred for body text |
| Black text on #3F437B | 2.30:1 | Fails | Lc 13.1 | Not readable |
| #3F437B text on white | 9.12:1 | AAA | Lc 90.9 | Preferred for body text |
| #3F437B text on black | 2.30:1 | Fails | Lc -11.4 | 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
#F4F5FA
oklch(97.1% 0.007 277.2)
-
Step 100
100
#E7E9F5
oklch(93.6% 0.016 278.5)
-
Step 200
200
#D4D8ED
oklch(88.6% 0.029 277.2)
-
Step 300
300
#B8BEE4
oklch(80.9% 0.054 278.1)
-
Step 400
400
#949BD7
oklch(70.6% 0.088 278.7)
-
Step 500
500
#7A82CC
oklch(63.1% 0.111 278)
-
Step 600
600
#646AB9
oklch(55.6% 0.122 278.4)
-
Step 700
700
#53589F
oklch(49.1% 0.113 278.3)
-
Step 800
800 (this color)
#3F437B
oklch(40.8% 0.093 278.3)
-
Step 900
900
#393D67
oklch(37.7% 0.072 278.2)
-
Step 950
950
#21243D
oklch(27% 0.047 277.6)
#3F437B 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) | #2D4B7D | 0.030 |
| Deuteranopia (no green cones) | #28467A | 0.030 |
| Tritanopia (no blue cones) | #2A4F59 | 0.081 |
| Achromatopsia (no color) | #484848 | 0.093 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #3F437B
#3F437B
oklch(40.8% 0.093 278.3)
- #564A00
#564A00
oklch(40.9% 0.085 98.6)
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 #3F437B, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Dark Slate Blue #483D8B ΔE 0.036
- Blueberry #464196 ΔE 0.047
- Cobalt #1E488F ΔE 0.048
- Twilight #4E518B ΔE 0.052
- Light Navy #155084 ΔE 0.052
- Dusk Blue #26538D ΔE 0.054
- Twilight Blue #0A437A ΔE 0.054
- Dusk #4E5481 ΔE 0.056
Use #3F437B 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.