#173B66
Closest named color: Marine Blue (#01386A). oklch(35% 0.086 254.7), rgb(23, 59, 102).
Aa
White text reads best on this color (11.32:1).
About this color
#173B66 is a dark, moderately saturated blue. In OKLCH its lightness is 35%, its chroma 0.086 and its hue 255°. Its hue sits on the cool side of the wheel. The nearest named color is Marine Blue (#01386A), ΔE 0.019 away. White text reads best on it, at 11.32:1.
| Hue family | Blues |
| Lightness | dark (35%) |
| Chroma | moderately saturated (0.086) |
| Temperature | cool |
| Nearest name | Marine Blue (#01386A) |
| Black text | 1.85:1 |
| White text | 11.32:1 |
Values
| HEX | #173B66 |
| RGB | rgb(23, 59, 102) |
| HSL | hsl(213, 63%, 25%) |
| OKLCH | oklch(35% 0.086 254.7) |
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 #173B66 | 11.32:1 | AAA | Lc -99.6 | Preferred for body text |
| Black text on #173B66 | 1.85:1 | Fails | Lc 8.0 | Not readable |
| #173B66 text on white | 11.32:1 | AAA | Lc 95.9 | Preferred for body text |
| #173B66 text on black | 1.85:1 | Fails | Lc 0.0 | 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
#F2F6FB
oklch(97.2% 0.008 253.9)
-
Step 100
100
#E2EBF6
oklch(93.7% 0.018 253.3)
-
Step 200
200
#CADBF1
oklch(88.6% 0.035 254.9)
-
Step 300
300
#A5C3EA
oklch(80.8% 0.064 255.1)
-
Step 400
400
#74A3E0
oklch(70.6% 0.103 255.3)
-
Step 500
500
#4E8BD7
oklch(63% 0.132 254.9)
-
Step 600
600
#2F74C4
oklch(55.6% 0.142 254.4)
-
Step 700
700
#2161AA
oklch(49.2% 0.133 254.5)
-
Step 800
800
#1E4F89
oklch(42.6% 0.11 254.7)
-
Step 900
900 (this color)
#173B66
oklch(35% 0.086 254.7)
-
Step 950
950
#132740
oklch(27% 0.054 254.9)
#173B66 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) | #273E68 | 0.021 |
| Deuteranopia (no green cones) | #1A3765 | 0.012 |
| Tritanopia (no blue cones) | #00454B | 0.066 |
| Achromatopsia (no color) | #3A3A3A | 0.086 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #173B66
#173B66
oklch(35% 0.086 254.7)
- #513400
#513400
oklch(35.1% 0.074 74.8)
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 #173B66, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Marine Blue #01386A ΔE 0.019
- Prussian Blue #1D3557 ΔE 0.029
- Twilight Blue #0A437A ΔE 0.038
- Dark Blue Grey #1F3B4D ΔE 0.045
- Marine #042E60 ΔE 0.046
- Midnight Green #073B4C ΔE 0.049
- Dark Grey Blue #29465B ΔE 0.049
- Charcoal #264653 ΔE 0.057
Use #173B66 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.