#173A73
Closest named color: Marine Blue (#01386A). oklch(35.7% 0.106 259.8), rgb(23, 58, 115).
Aa
White text reads best on this color (11.11:1).
About this color
#173A73 is a dark, moderately saturated blue. In OKLCH its lightness is 36%, its chroma 0.106 and its hue 260°. Its hue sits on the cool side of the wheel. The nearest named color is Marine Blue (#01386A), ΔE 0.023 away. White text reads best on it, at 11.11:1.
| Hue family | Blues |
| Lightness | dark (36%) |
| Chroma | moderately saturated (0.106) |
| Temperature | cool |
| Nearest name | Marine Blue (#01386A) |
| Black text | 1.88:1 |
| White text | 11.11:1 |
Values
| HEX | #173A73 |
| RGB | rgb(23, 58, 115) |
| HSL | hsl(217, 67%, 27%) |
| OKLCH | oklch(35.7% 0.106 259.8) |
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 #173A73 | 11.11:1 | AAA | Lc -99.2 | Preferred for body text |
| Black text on #173A73 | 1.88:1 | Fails | Lc 8.6 | Not readable |
| #173A73 text on white | 11.11:1 | AAA | Lc 95.3 | Preferred for body text |
| #173A73 text on black | 1.88:1 | Fails | Lc -7.3 | 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
#F1F6FD
oklch(97.1% 0.011 256.7)
-
Step 100
100
#E1EBFA
oklch(93.7% 0.023 258.4)
-
Step 200
200
#C8DAF7
oklch(88.4% 0.045 259.9)
-
Step 300
300
#A3C2F5
oklch(80.9% 0.08 260.3)
-
Step 400
400
#70A1F0
oklch(70.8% 0.128 259.6)
-
Step 500
500
#4A87EA
oklch(63.1% 0.162 259.6)
-
Step 600
600
#2C6ED9
oklch(55.6% 0.177 259.8)
-
Step 700
700
#1F5BBC
oklch(49.1% 0.165 259.9)
-
Step 800
800
#1B4B98
oklch(42.7% 0.137 259.7)
-
Step 900
900 (this color)
#173A73
oklch(35.7% 0.106 259.8)
-
Step 950
950
#112647
oklch(27.1% 0.067 259.1)
#173A73 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) | #1B4075 | 0.019 |
| Deuteranopia (no green cones) | #023872 | 0.016 |
| Tritanopia (no blue cones) | #004851 | 0.083 |
| Achromatopsia (no color) | #3C3C3C | 0.106 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #173A73
#173A73
oklch(35.7% 0.106 259.8)
- #513700
#513700
oklch(35.8% 0.074 79.2)
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 #173A73, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Marine Blue #01386A ΔE 0.023
- Twilight Blue #0A437A ΔE 0.027
- Prussian Blue #1D3557 ΔE 0.049
- Marine #042E60 ΔE 0.051
- Cobalt #1E488F ΔE 0.060
- Dark Grey Blue #29465B ΔE 0.065
- Light Navy #155084 ΔE 0.068
- Dark Blue Grey #1F3B4D ΔE 0.068
Use #173A73 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.