#373B8A
Closest named color: Dark Slate Blue (#483D8B). oklch(39.6% 0.129 276.6), rgb(55, 59, 138).
Aa
White text reads best on this color (9.74:1).
About this color
#373B8A is a dark, moderately saturated blue. In OKLCH its lightness is 40%, its chroma 0.129 and its hue 277°. Its hue sits on the cool side of the wheel. The nearest named color is Dark Slate Blue (#483D8B), ΔE 0.028 away. White text reads best on it, at 9.74:1.
| Hue family | Blues |
| Lightness | dark (40%) |
| Chroma | moderately saturated (0.129) |
| Temperature | cool |
| Nearest name | Dark Slate Blue (#483D8B) |
| Black text | 2.15:1 |
| White text | 9.74:1 |
Values
| HEX | #373B8A |
| RGB | rgb(55, 59, 138) |
| HSL | hsl(237, 43%, 38%) |
| OKLCH | oklch(39.6% 0.129 276.6) |
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 #373B8A | 9.74:1 | AAA | Lc -96.5 | Preferred for body text |
| Black text on #373B8A | 2.15:1 | Fails | Lc 11.7 | Not readable |
| #373B8A text on white | 9.74:1 | AAA | Lc 92.3 | Preferred for body text |
| #373B8A text on black | 2.15:1 | Fails | Lc -10.1 | 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
#F3F5FE
oklch(97.1% 0.012 276.1)
-
Step 100
100
#E4E9FD
oklch(93.6% 0.028 274.7)
-
Step 200
200
#CFD7FD
oklch(88.5% 0.053 275.9)
-
Step 300
300
#B0BBFF
oklch(80.8% 0.097 276.9)
-
Step 400
400
#8995FF
oklch(70.7% 0.154 276.8)
-
Step 500
500
#6E76FE
oklch(63% 0.199 276.5)
-
Step 600
600
#595AED
oklch(55.5% 0.216 276.5)
-
Step 700
700
#4A49CE
oklch(49.1% 0.199 276.5)
-
Step 800
800
#3C3DA7
oklch(42.7% 0.166 276.4)
-
Step 900
900 (this color)
#373B8A
oklch(39.6% 0.129 276.6)
-
Step 950
950
#1D204D
oklch(26.9% 0.082 276.5)
#373B8A 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) | #00488D | 0.051 |
| Deuteranopia (no green cones) | #004188 | 0.048 |
| Tritanopia (no blue cones) | #004E5C | 0.114 |
| Achromatopsia (no color) | #444444 | 0.130 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #373B8A
#373B8A
oklch(39.6% 0.129 276.6)
- #534600
#534600
oklch(39.6% 0.082 97)
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 #373B8A, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Dark Slate Blue #483D8B ΔE 0.028
- Blueberry #464196 ΔE 0.035
- Cobalt #1E488F ΔE 0.041
- Twilight Blue #0A437A ΔE 0.055
- Sapphire #2138AB ΔE 0.061
- Light Navy #155084 ΔE 0.065
- Dusk Blue #26538D ΔE 0.066
- Twilight #4E518B ΔE 0.073
Use #373B8A 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.