#173F87
Closest named color: Twilight Blue (#0A437A). oklch(38.5% 0.129 261), rgb(23, 63, 135).
Aa
White text reads best on this color (10.01:1).
About this color
#173F87 is a dark, moderately saturated blue. In OKLCH its lightness is 38%, its chroma 0.129 and its hue 261°. Its hue sits on the cool side of the wheel. The nearest named color is Twilight Blue (#0A437A), ΔE 0.027 away. White text reads best on it, at 10.01:1.
| Hue family | Blues |
| Lightness | dark (38%) |
| Chroma | moderately saturated (0.129) |
| Temperature | cool |
| Nearest name | Twilight Blue (#0A437A) |
| Black text | 2.09:1 |
| White text | 10.01:1 |
Values
| HEX | #173F87 |
| RGB | rgb(23, 63, 135) |
| HSL | hsl(219, 71%, 31%) |
| OKLCH | oklch(38.5% 0.129 261) |
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 #173F87 | 10.01:1 | AAA | Lc -96.9 | Preferred for body text |
| Black text on #173F87 | 2.09:1 | Fails | Lc 11.2 | Not readable |
| #173F87 text on white | 10.01:1 | AAA | Lc 92.8 | Preferred for body text |
| #173F87 text on black | 2.09:1 | Fails | Lc -9.7 | 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
#F1F6FE
oklch(97.2% 0.012 259.8)
-
Step 100
100
#E0EBFD
oklch(93.7% 0.027 260.3)
-
Step 200
200
#C5DAFD
oklch(88.4% 0.054 260.6)
-
Step 300
300
#9EC1FF
oklch(80.8% 0.096 261.6)
-
Step 400
400
#689FFF
oklch(70.7% 0.153 260.8)
-
Step 500
500
#3E83FF
oklch(63.2% 0.198 261)
-
Step 600
600
#1C68EE
oklch(55.6% 0.215 261.1)
-
Step 700
700
#0E55CF
oklch(49% 0.2 261.1)
-
Step 800
800
#1047A7
oklch(42.7% 0.165 261)
-
Step 900
900 (this color)
#173F87
oklch(38.5% 0.129 261)
-
Step 950
950
#0D244E
oklch(27% 0.083 261.2)
#173F87 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) | #0D488A | 0.025 |
| Deuteranopia (no green cones) | #003D86 | 0.015 |
| Tritanopia (no blue cones) | #00515C | 0.101 |
| Achromatopsia (no color) | #424242 | 0.129 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #173F87
#173F87
oklch(38.5% 0.129 261)
- #593E00
#593E00
oklch(38.4% 0.079 80.8)
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 #173F87, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Twilight Blue #0A437A ΔE 0.027
- Cobalt #1E488F ΔE 0.029
- Light Navy #155084 ΔE 0.050
- Marine Blue #01386A ΔE 0.056
- Dusk Blue #26538D ΔE 0.061
- Sapphire #2138AB ΔE 0.062
- Dark Slate Blue #483D8B ΔE 0.062
- Deep Sea Blue #015482 ΔE 0.063
Use #173F87 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.