#373F88
Closest named color: Dark Slate Blue (#483D8B). oklch(40.2% 0.121 274.9), rgb(55, 63, 136).
Aa
White text reads best on this color (9.42:1).
About this color
#373F88 is a dark, moderately saturated blue. In OKLCH its lightness is 40%, its chroma 0.121 and its hue 275°. Its hue sits on the cool side of the wheel. The nearest named color is Dark Slate Blue (#483D8B), ΔE 0.027 away. White text reads best on it, at 9.42:1.
| Hue family | Blues |
| Lightness | dark (40%) |
| Chroma | moderately saturated (0.121) |
| Temperature | cool |
| Nearest name | Dark Slate Blue (#483D8B) |
| Black text | 2.22:1 |
| White text | 9.42:1 |
Values
| HEX | #373F88 |
| RGB | rgb(55, 63, 136) |
| HSL | hsl(234, 42%, 37%) |
| OKLCH | oklch(40.2% 0.121 274.9) |
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 #373F88 | 9.42:1 | AAA | Lc -95.8 | Preferred for body text |
| Black text on #373F88 | 2.22:1 | Fails | Lc 12.4 | Not readable |
| #373F88 text on white | 9.42:1 | AAA | Lc 91.5 | Preferred for body text |
| #373F88 text on black | 2.22:1 | Fails | Lc -10.8 | 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 800.
-
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
#B3BEEF
oklch(81% 0.07 274.9)
-
Step 400
400
#8C9BE7
oklch(70.8% 0.113 274.6)
-
Step 500
500
#7180DF
oklch(63.1% 0.143 274.8)
-
Step 600
600
#5B67CD
oklch(55.6% 0.156 275.1)
-
Step 700
700
#4B55B2
oklch(49.1% 0.146 275)
-
Step 800
800 (this color)
#373F88
oklch(40.2% 0.121 274.9)
-
Step 900
900
#343C73
oklch(37.8% 0.094 274.8)
-
Step 950
950
#1E2343
oklch(26.9% 0.06 275)
#373F88 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) | #154A8B | 0.041 |
| Deuteranopia (no green cones) | #024386 | 0.045 |
| Tritanopia (no blue cones) | #00505D | 0.107 |
| Achromatopsia (no color) | #464646 | 0.121 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #373F88
#373F88
oklch(40.2% 0.121 274.9)
- #564700
#564700
oklch(40.2% 0.082 95.2)
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 #373F88, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Dark Slate Blue #483D8B ΔE 0.027
- Blueberry #464196 ΔE 0.033
- Cobalt #1E488F ΔE 0.034
- Twilight Blue #0A437A ΔE 0.050
- Light Navy #155084 ΔE 0.055
- Dusk Blue #26538D ΔE 0.056
- Twilight #4E518B ΔE 0.064
- Sapphire #2138AB ΔE 0.066
Use #373F88 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.