#373F81
Closest named color: Dark Slate Blue (#483D8B). oklch(39.7% 0.11 275), rgb(55, 63, 129).
Aa
White text reads best on this color (9.58:1).
About this color
#373F81 is a dark, moderately saturated blue. In OKLCH its lightness is 40%, its chroma 0.110 and its hue 275°. Its hue sits on the cool side of the wheel. The nearest named color is Dark Slate Blue (#483D8B), ΔE 0.032 away. White text reads best on it, at 9.58:1.
| Hue family | Blues |
| Lightness | dark (40%) |
| Chroma | moderately saturated (0.110) |
| Temperature | cool |
| Nearest name | Dark Slate Blue (#483D8B) |
| Black text | 2.19:1 |
| White text | 9.58:1 |
Values
| HEX | #373F81 |
| RGB | rgb(55, 63, 129) |
| HSL | hsl(234, 40%, 36%) |
| OKLCH | oklch(39.7% 0.11 275) |
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 #373F81 | 9.58:1 | AAA | Lc -96.3 | Preferred for body text |
| Black text on #373F81 | 2.19:1 | Fails | Lc 12.0 | Not readable |
| #373F81 text on white | 9.58:1 | AAA | Lc 92.0 | Preferred for body text |
| #373F81 text on black | 2.19:1 | Fails | Lc -10.4 | 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
#F3F5FD
oklch(97.1% 0.011 274.9)
-
Step 100
100
#E5E9FA
oklch(93.6% 0.023 275.4)
-
Step 200
200
#D0D7F8
oklch(88.4% 0.046 276)
-
Step 300
300
#B1BDF6
oklch(80.9% 0.082 275.2)
-
Step 400
400
#8999F2
oklch(70.8% 0.131 274.8)
-
Step 500
500
#6E7CEE
oklch(63.1% 0.17 275.2)
-
Step 600
600
#5862DC
oklch(55.5% 0.184 275.1)
-
Step 700
700
#4851BF
oklch(49.2% 0.17 274.7)
-
Step 800
800
#3B439A
oklch(42.7% 0.14 274.8)
-
Step 900
900 (this color)
#373F81
oklch(39.7% 0.11 275)
-
Step 950
950
#1D2248
oklch(27% 0.07 275)
#373F81 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) | #1E4883 | 0.034 |
| Deuteranopia (no green cones) | #144280 | 0.037 |
| Tritanopia (no blue cones) | #0F4E5A | 0.097 |
| Achromatopsia (no color) | #454545 | 0.110 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #373F81
#373F81
oklch(39.7% 0.11 275)
- #554600
#554600
oklch(39.8% 0.082 95)
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 #373F81, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Dark Slate Blue #483D8B ΔE 0.032
- Cobalt #1E488F ΔE 0.039
- Blueberry #464196 ΔE 0.042
- Twilight Blue #0A437A ΔE 0.045
- Light Navy #155084 ΔE 0.054
- Dusk Blue #26538D ΔE 0.057
- Twilight #4E518B ΔE 0.065
- Deep Sea Blue #015482 ΔE 0.067
Use #373F81 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.