#373F78
Closest named color: Twilight Blue (#0A437A). oklch(39.1% 0.096 275), rgb(55, 63, 120).
Aa
White text reads best on this color (9.79:1).
About this color
#373F78 is a dark, moderately saturated blue. In OKLCH its lightness is 39%, its chroma 0.096 and its hue 275°. Its hue sits on the cool side of the wheel. The nearest named color is Twilight Blue (#0A437A), ΔE 0.042 away. White text reads best on it, at 9.79:1.
| Hue family | Blues |
| Lightness | dark (39%) |
| Chroma | moderately saturated (0.096) |
| Temperature | cool |
| Nearest name | Twilight Blue (#0A437A) |
| Black text | 2.14:1 |
| White text | 9.79:1 |
Values
| HEX | #373F78 |
| RGB | rgb(55, 63, 120) |
| HSL | hsl(233, 37%, 34%) |
| OKLCH | oklch(39.1% 0.096 275) |
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 #373F78 | 9.79:1 | AAA | Lc -96.7 | Preferred for body text |
| Black text on #373F78 | 2.14:1 | Fails | Lc 11.4 | Not readable |
| #373F78 text on white | 9.79:1 | AAA | Lc 92.6 | Preferred for body text |
| #373F78 text on black | 2.14:1 | 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
#F3F5FC
oklch(97.1% 0.01 273.4)
-
Step 100
100
#E5E9F8
oklch(93.5% 0.021 274)
-
Step 200
200
#D1D8F4
oklch(88.6% 0.039 274.4)
-
Step 300
300
#B3BEF0
oklch(81% 0.072 275)
-
Step 400
400
#8C9AE8
oklch(70.7% 0.115 275.3)
-
Step 500
500
#717FE1
oklch(63.1% 0.147 275.2)
-
Step 600
600
#5A66CF
oklch(55.5% 0.161 275)
-
Step 700
700
#4B54B3
oklch(49% 0.149 275.4)
-
Step 800
800
#3D4691
oklch(42.8% 0.123 274.8)
-
Step 900
900 (this color)
#373F78
oklch(39.1% 0.096 275)
-
Step 950
950
#1E2344
oklch(27% 0.061 275)
#373F78 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) | #26467A | 0.027 |
| Deuteranopia (no green cones) | #1F4177 | 0.029 |
| Tritanopia (no blue cones) | #1A4B55 | 0.085 |
| Achromatopsia (no color) | #444444 | 0.096 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #373F78
#373F78
oklch(39.1% 0.096 275)
- #534400
#534400
oklch(39.1% 0.08 94.6)
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 #373F78, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Twilight Blue #0A437A ΔE 0.042
- Dark Slate Blue #483D8B ΔE 0.043
- Cobalt #1E488F ΔE 0.048
- Light Navy #155084 ΔE 0.055
- Blueberry #464196 ΔE 0.056
- Dusk Blue #26538D ΔE 0.062
- Dark Grey Blue #29465B ΔE 0.062
- Marine Blue #01386A ΔE 0.065
Use #373F78 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.