#173B88
Closest named color: Twilight Blue (#0A437A). oklch(37.7% 0.136 262.8), rgb(23, 59, 136).
Aa
White text reads best on this color (10.40:1).
About this color
#173B88 is a dark, moderately saturated blue. In OKLCH its lightness is 38%, its chroma 0.136 and its hue 263°. Its hue sits on the cool side of the wheel. The nearest named color is Twilight Blue (#0A437A), ΔE 0.035 away. White text reads best on it, at 10.40:1.
| Hue family | Blues |
| Lightness | dark (38%) |
| Chroma | moderately saturated (0.136) |
| Temperature | cool |
| Nearest name | Twilight Blue (#0A437A) |
| Black text | 2.01:1 |
| White text | 10.40:1 |
Values
| HEX | #173B88 |
| RGB | rgb(23, 59, 136) |
| HSL | hsl(221, 71%, 31%) |
| OKLCH | oklch(37.7% 0.136 262.8) |
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 #173B88 | 10.40:1 | AAA | Lc -97.7 | Preferred for body text |
| Black text on #173B88 | 2.01:1 | Fails | Lc 10.3 | Not readable |
| #173B88 text on white | 10.40:1 | AAA | Lc 93.6 | Preferred for body text |
| #173B88 text on black | 2.01:1 | Fails | Lc -8.9 | 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
#6C9EFF
oklch(70.7% 0.152 262.5)
-
Step 500
500
#4581FF
oklch(63.1% 0.198 262.9)
-
Step 600
600
#2264F4
oklch(55.5% 0.226 262.8)
-
Step 700
700
#1652D5
oklch(49.1% 0.21 262.8)
-
Step 800
800
#1544AC
oklch(42.7% 0.174 262.9)
-
Step 900
900 (this color)
#173B88
oklch(37.7% 0.136 262.8)
-
Step 950
950
#0E2350
oklch(26.9% 0.087 263)
#173B88 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 | 0.027 |
| Deuteranopia (no green cones) | #003B86 | 0.013 |
| Tritanopia (no blue cones) | #004E5B | 0.105 |
| Achromatopsia (no color) | #404040 | 0.136 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #173B88
#173B88
oklch(37.7% 0.136 262.8)
- #553D00
#553D00
oklch(37.7% 0.077 83.5)
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 #173B88, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Twilight Blue #0A437A ΔE 0.035
- Cobalt #1E488F ΔE 0.039
- Marine Blue #01386A ΔE 0.055
- Sapphire #2138AB ΔE 0.059
- Light Navy #155084 ΔE 0.062
- Dark Slate Blue #483D8B ΔE 0.065
- Blueberry #464196 ΔE 0.068
- Dusk Blue #26538D ΔE 0.072
Use #173B88 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.