#173A88
Closest named color: Twilight Blue (#0A437A). oklch(37.5% 0.137 263.2), rgb(23, 58, 136).
Aa
White text reads best on this color (10.51:1).
About this color
#173A88 is a dark, moderately saturated blue. In OKLCH its lightness is 37%, its chroma 0.137 and its hue 263°. Its hue sits on the cool side of the wheel. The nearest named color is Twilight Blue (#0A437A), ΔE 0.037 away. White text reads best on it, at 10.51:1.
| Hue family | Blues |
| Lightness | dark (37%) |
| Chroma | moderately saturated (0.137) |
| Temperature | cool |
| Nearest name | Twilight Blue (#0A437A) |
| Black text | 1.99:1 |
| White text | 10.51:1 |
Values
| HEX | #173A88 |
| RGB | rgb(23, 58, 136) |
| HSL | hsl(221, 71%, 31%) |
| OKLCH | oklch(37.5% 0.137 263.2) |
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 #173A88 | 10.51:1 | AAA | Lc -97.9 | Preferred for body text |
| Black text on #173A88 | 1.99:1 | Fails | Lc 10.1 | Not readable |
| #173A88 text on white | 10.51:1 | AAA | Lc 93.9 | Preferred for body text |
| #173A88 text on black | 1.99:1 | Fails | Lc -8.7 | 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
#F1F6FF
oklch(97.2% 0.013 262.4)
-
Step 100
100
#E0EAFE
oklch(93.6% 0.029 264.4)
-
Step 200
200
#C6DAFF
oklch(88.5% 0.056 262.8)
-
Step 300
300
#A0C1FF
oklch(80.9% 0.095 262.7)
-
Step 400
400
#6D9DFF
oklch(70.6% 0.153 263.3)
-
Step 500
500
#4681FF
oklch(63.1% 0.198 263.1)
-
Step 600
600
#2464F6
oklch(55.7% 0.228 263.1)
-
Step 700
700
#1851D6
oklch(49.1% 0.212 263.2)
-
Step 800
800
#1644AD
oklch(42.8% 0.175 263.1)
-
Step 900
900 (this color)
#173A88
oklch(37.5% 0.137 263.2)
-
Step 950
950
#0F2350
oklch(27% 0.087 263.6)
#173A88 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) | #00458B | 0.030 |
| Deuteranopia (no green cones) | #003A86 | 0.014 |
| Tritanopia (no blue cones) | #004D5B | 0.105 |
| Achromatopsia (no color) | #3F3F3F | 0.137 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #173A88
#173A88
oklch(37.5% 0.137 263.2)
- #543C00
#543C00
oklch(37.3% 0.077 83.1)
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 #173A88, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Twilight Blue #0A437A ΔE 0.037
- Cobalt #1E488F ΔE 0.041
- Marine Blue #01386A ΔE 0.055
- Sapphire #2138AB ΔE 0.059
- Light Navy #155084 ΔE 0.064
- Dark Slate Blue #483D8B ΔE 0.066
- Blueberry #464196 ΔE 0.069
- Dusk Blue #26538D ΔE 0.074
Use #173A88 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.