#173387
Closest named color: Twilight Blue (#0A437A). oklch(35.9% 0.145 265.4), rgb(23, 51, 135).
Aa
White text reads best on this color (11.29:1).
About this color
#173387 is a dark, vivid blue. In OKLCH its lightness is 36%, its chroma 0.145 and its hue 265°. Its hue sits on the cool side of the wheel. The nearest named color is Twilight Blue (#0A437A), ΔE 0.050 away. White text reads best on it, at 11.29:1.
| Hue family | Blues |
| Lightness | dark (36%) |
| Chroma | vivid (0.145) |
| Temperature | cool |
| Nearest name | Twilight Blue (#0A437A) |
| Black text | 1.85:1 |
| White text | 11.29:1 |
Values
| HEX | #173387 |
| RGB | rgb(23, 51, 135) |
| HSL | hsl(225, 71%, 31%) |
| OKLCH | oklch(35.9% 0.145 265.4) |
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 #173387 | 11.29:1 | AAA | Lc -99.3 | Preferred for body text |
| Black text on #173387 | 1.85:1 | Fails | Lc 8.4 | Not readable |
| #173387 text on white | 11.29:1 | AAA | Lc 95.5 | Preferred for body text |
| #173387 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
#F1F6FF
oklch(97.2% 0.013 262.4)
-
Step 100
100
#E0EAFF
oklch(93.6% 0.03 265.3)
-
Step 200
200
#C8D9FF
oklch(88.5% 0.056 266.2)
-
Step 300
300
#A3C0FF
oklch(80.9% 0.095 265.2)
-
Step 400
400
#729CFF
oklch(70.6% 0.153 265.4)
-
Step 500
500
#4E7FFF
oklch(63% 0.198 265.3)
-
Step 600
600
#2D5FFD
oklch(55.6% 0.24 265.3)
-
Step 700
700
#214CDD
oklch(49% 0.225 265.3)
-
Step 800
800
#1C40B2
oklch(42.7% 0.185 265.3)
-
Step 900
900 (this color)
#173387
oklch(35.9% 0.145 265.4)
-
Step 950
950
#102252
oklch(27% 0.091 265.2)
#173387 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) | #00408A | 0.034 |
| Deuteranopia (no green cones) | #003585 | 0.014 |
| Tritanopia (no blue cones) | #004958 | 0.112 |
| Achromatopsia (no color) | #3A3A3A | 0.145 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #173387
#173387
oklch(35.9% 0.145 265.4)
- #4E3900
#4E3900
oklch(35.8% 0.073 85.4)
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 #173387, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Twilight Blue #0A437A ΔE 0.050
- Marine Blue #01386A ΔE 0.055
- Cobalt #1E488F ΔE 0.059
- Royal #0C1793 ΔE 0.060
- Sapphire #2138AB ΔE 0.063
- Marine #042E60 ΔE 0.072
- Midnight Blue #191970 ΔE 0.073
- Dark Slate Blue #483D8B ΔE 0.076
Use #173387 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.