#3F378B
Closest named color: Dark Slate Blue (#483D8B). oklch(39.5% 0.135 282.6), rgb(63, 55, 139).
Aa
White text reads best on this color (9.85:1).
About this color
#3F378B is a dark, moderately saturated purple. In OKLCH its lightness is 40%, its chroma 0.135 and its hue 283°. Its hue sits on the cool side of the wheel. The nearest named color is Dark Slate Blue (#483D8B), ΔE 0.023 away. White text reads best on it, at 9.85:1.
| Hue family | Purples |
| Lightness | dark (40%) |
| Chroma | moderately saturated (0.135) |
| Temperature | cool |
| Nearest name | Dark Slate Blue (#483D8B) |
| Black text | 2.13:1 |
| White text | 9.85:1 |
Values
| HEX | #3F378B |
| RGB | rgb(63, 55, 139) |
| HSL | hsl(246, 43%, 38%) |
| OKLCH | oklch(39.5% 0.135 282.6) |
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 #3F378B | 9.85:1 | AAA | Lc -96.7 | Preferred for body text |
| Black text on #3F378B | 2.13:1 | Fails | Lc 11.4 | Not readable |
| #3F378B text on white | 9.85:1 | AAA | Lc 92.5 | Preferred for body text |
| #3F378B text on black | 2.13:1 | Fails | Lc -9.9 | 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 900.
-
Step 50
50
#F4F5FF
oklch(97.2% 0.013 281.6)
-
Step 100
100
#E6E8FE
oklch(93.6% 0.03 281.7)
-
Step 200
200
#D3D5FE
oklch(88.5% 0.056 283)
-
Step 300
300
#B7B9FF
oklch(80.9% 0.098 282.7)
-
Step 400
400
#9491FF
oklch(70.7% 0.158 282.8)
-
Step 500
500
#7C70FF
oklch(63.1% 0.205 282.6)
-
Step 600
600
#6852EF
oklch(55.5% 0.225 282.6)
-
Step 700
700
#5741D0
oklch(49% 0.209 282.5)
-
Step 800
800
#4737A8
oklch(42.7% 0.173 282.7)
-
Step 900
900 (this color)
#3F378B
oklch(39.5% 0.135 282.6)
-
Step 950
950
#221E4E
oklch(27% 0.085 282.8)
#3F378B 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) | #00468E | 0.064 |
| Deuteranopia (no green cones) | #004089 | 0.061 |
| Tritanopia (no blue cones) | #1E4B5B | 0.116 |
| Achromatopsia (no color) | #434343 | 0.135 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #3F378B
#3F378B
oklch(39.5% 0.135 282.6)
- #4F4800
#4F4800
oklch(39.6% 0.083 103.2)
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 #3F378B, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Dark Slate Blue #483D8B ΔE 0.023
- Blueberry #464196 ΔE 0.033
- Cobalt #1E488F ΔE 0.055
- Sapphire #2138AB ΔE 0.065
- Twilight Blue #0A437A ΔE 0.069
- Rebecca Purple #663399 ΔE 0.074
- Twilight #4E518B ΔE 0.077
- Dusk Blue #26538D ΔE 0.077
Use #3F378B 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.