#373A69
Closest named color: Prussian Blue (#1D3557). oklch(37% 0.08 278.9), rgb(55, 58, 105).
Aa
White text reads best on this color (10.65:1).
About this color
#373A69 is a dark, moderately saturated blue. In OKLCH its lightness is 37%, its chroma 0.080 and its hue 279°. Its hue sits on the cool side of the wheel. The nearest named color is Prussian Blue (#1D3557), ΔE 0.052 away. White text reads best on it, at 10.65:1.
| Hue family | Blues |
| Lightness | dark (37%) |
| Chroma | moderately saturated (0.080) |
| Temperature | cool |
| Nearest name | Prussian Blue (#1D3557) |
| Black text | 1.97:1 |
| White text | 10.65:1 |
Values
| HEX | #373A69 |
| RGB | rgb(55, 58, 105) |
| HSL | hsl(236, 31%, 31%) |
| OKLCH | oklch(37% 0.08 278.9) |
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 #373A69 | 10.65:1 | AAA | Lc -98.5 | Preferred for body text |
| Black text on #373A69 | 1.97:1 | Fails | Lc 9.3 | Not readable |
| #373A69 text on white | 10.65:1 | AAA | Lc 94.6 | Preferred for body text |
| #373A69 text on black | 1.97:1 | Fails | Lc -8.0 | 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
#F4F5FB
oklch(97.1% 0.008 278.6)
-
Step 100
100
#E7E9F6
oklch(93.6% 0.018 279.1)
-
Step 200
200
#D4D7F0
oklch(88.5% 0.034 280.2)
-
Step 300
300
#B8BDE8
oklch(80.9% 0.061 279.7)
-
Step 400
400
#939ADC
oklch(70.6% 0.097 278.9)
-
Step 500
500
#7A80D2
oklch(63% 0.123 279.1)
-
Step 600
600
#6468BF
oklch(55.6% 0.133 279.1)
-
Step 700
700
#5356A5
oklch(49% 0.124 279.1)
-
Step 800
800
#444786
oklch(42.7% 0.103 279)
-
Step 900
900 (this color)
#373A69
oklch(37% 0.08 278.9)
-
Step 950
950
#21233F
oklch(26.9% 0.052 279.2)
#373A69 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) | #28406B | 0.025 |
| Deuteranopia (no green cones) | #253C68 | 0.025 |
| Tritanopia (no blue cones) | #26444C | 0.071 |
| Achromatopsia (no color) | #3E3E3E | 0.080 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #373A69
#373A69
oklch(37% 0.08 278.9)
- #4A4000
#4A4000
oklch(37% 0.077 99.2)
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 #373A69, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Prussian Blue #1D3557 ΔE 0.052
- Dark Grey Blue #29465B ΔE 0.052
- Twilight Blue #0A437A ΔE 0.052
- Marine Blue #01386A ΔE 0.056
- Dark Blue Grey #1F3B4D ΔE 0.062
- Charcoal #264653 ΔE 0.064
- Dark Slate Blue #483D8B ΔE 0.064
- Cobalt #1E488F ΔE 0.072
Use #373A69 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.