#373A78
Closest named color: Dark Slate Blue (#483D8B). oklch(38% 0.104 278.2), rgb(55, 58, 120).
Aa
White text reads best on this color (10.29:1).
About this color
#373A78 is a dark, moderately saturated blue. In OKLCH its lightness is 38%, its chroma 0.104 and its hue 278°. Its hue sits on the cool side of the wheel. The nearest named color is Dark Slate Blue (#483D8B), ΔE 0.043 away. White text reads best on it, at 10.29:1.
| Hue family | Blues |
| Lightness | dark (38%) |
| Chroma | moderately saturated (0.104) |
| Temperature | cool |
| Nearest name | Dark Slate Blue (#483D8B) |
| Black text | 2.03:1 |
| White text | 10.29:1 |
Values
| HEX | #373A78 |
| RGB | rgb(55, 58, 120) |
| HSL | hsl(237, 37%, 34%) |
| OKLCH | oklch(38% 0.104 278.2) |
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 #373A78 | 10.29:1 | AAA | Lc -97.8 | Preferred for body text |
| Black text on #373A78 | 2.03:1 | Fails | Lc 10.2 | Not readable |
| #373A78 text on white | 10.29:1 | AAA | Lc 93.7 | Preferred for body text |
| #373A78 text on black | 2.03:1 | Fails | Lc -8.8 | 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
#F4F5FD
oklch(97.2% 0.011 280.5)
-
Step 100
100
#E6E9F9
oklch(93.6% 0.022 277.5)
-
Step 200
200
#D2D7F6
oklch(88.5% 0.043 278.2)
-
Step 300
300
#B4BCF3
oklch(80.8% 0.078 278.1)
-
Step 400
400
#8F98ED
oklch(70.7% 0.124 278.1)
-
Step 500
500
#757CE7
oklch(63.1% 0.159 278)
-
Step 600
600
#6062D5
oklch(55.6% 0.173 278.4)
-
Step 700
700
#4F51B9
oklch(49.2% 0.16 277.9)
-
Step 800
800
#414396
oklch(42.8% 0.133 278.1)
-
Step 900
900 (this color)
#373A78
oklch(38% 0.104 278.2)
-
Step 950
950
#202246
oklch(27.1% 0.066 278.6)
#373A78 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) | #1C437A | 0.038 |
| Deuteranopia (no green cones) | #153E77 | 0.039 |
| Tritanopia (no blue cones) | #1B4853 | 0.091 |
| Achromatopsia (no color) | #404040 | 0.104 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #373A78
#373A78
oklch(38% 0.104 278.2)
- #4E4200
#4E4200
oklch(38% 0.078 97.4)
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 #373A78, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Dark Slate Blue #483D8B ΔE 0.043
- Twilight Blue #0A437A ΔE 0.047
- Cobalt #1E488F ΔE 0.054
- Blueberry #464196 ΔE 0.058
- Marine Blue #01386A ΔE 0.061
- Light Navy #155084 ΔE 0.066
- Dark Grey Blue #29465B ΔE 0.070
- Prussian Blue #1D3557 ΔE 0.070
Use #373A78 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.