#3F437F
Closest named color: Dark Slate Blue (#483D8B). oklch(41% 0.099 278.2), rgb(63, 67, 127).
Aa
White text reads best on this color (9.04:1).
About this color
#3F437F is a dark, moderately saturated blue. In OKLCH its lightness is 41%, its chroma 0.099 and its hue 278°. Its hue sits on the cool side of the wheel. The nearest named color is Dark Slate Blue (#483D8B), ΔE 0.030 away. White text reads best on it, at 9.04:1.
| Hue family | Blues |
| Lightness | dark (41%) |
| Chroma | moderately saturated (0.099) |
| Temperature | cool |
| Nearest name | Dark Slate Blue (#483D8B) |
| Black text | 2.32:1 |
| White text | 9.04:1 |
Values
| HEX | #3F437F |
| RGB | rgb(63, 67, 127) |
| HSL | hsl(236, 34%, 37%) |
| OKLCH | oklch(41% 0.099 278.2) |
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 #3F437F | 9.04:1 | AAA | Lc -95.1 | Preferred for body text |
| Black text on #3F437F | 2.32:1 | Fails | Lc 13.3 | Not readable |
| #3F437F text on white | 9.04:1 | AAA | Lc 90.7 | Preferred for body text |
| #3F437F text on black | 2.32:1 | Fails | Lc -11.7 | 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
#F4F5FB
oklch(97.1% 0.008 278.6)
-
Step 100
100
#E7E9F5
oklch(93.6% 0.016 278.5)
-
Step 200
200
#D4D8EF
oklch(88.6% 0.032 277.9)
-
Step 300
300
#B7BEE6
oklch(80.9% 0.057 277.3)
-
Step 400
400
#939BDA
oklch(70.7% 0.092 278.2)
-
Step 500
500
#7981D0
oklch(63.1% 0.119 278)
-
Step 600
600
#6369BD
oklch(55.6% 0.129 278.2)
-
Step 700
700
#5257A3
oklch(49% 0.12 278.1)
-
Step 800
800 (this color)
#3F437F
oklch(41% 0.099 278.2)
-
Step 900
900
#383C6A
oklch(37.6% 0.078 278.2)
-
Step 950
950
#21243E
oklch(27.1% 0.048 277.6)
#3F437F 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) | #2A4B81 | 0.032 |
| Deuteranopia (no green cones) | #25467E | 0.033 |
| Tritanopia (no blue cones) | #27505B | 0.087 |
| Achromatopsia (no color) | #494949 | 0.099 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #3F437F
#3F437F
oklch(41% 0.099 278.2)
- #574A00
#574A00
oklch(41% 0.085 97.6)
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 #3F437F, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Dark Slate Blue #483D8B ΔE 0.030
- Blueberry #464196 ΔE 0.041
- Cobalt #1E488F ΔE 0.045
- Twilight #4E518B ΔE 0.050
- Dusk Blue #26538D ΔE 0.051
- Light Navy #155084 ΔE 0.052
- Twilight Blue #0A437A ΔE 0.055
- Dusk #4E5481 ΔE 0.056
Use #3F437F 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.