#173F7E
Closest named color: Twilight Blue (#0A437A). oklch(37.8% 0.116 259.4), rgb(23, 63, 126).
Aa
White text reads best on this color (10.25:1).
About this color
#173F7E is a dark, moderately saturated blue. In OKLCH its lightness is 38%, its chroma 0.116 and its hue 259°. Its hue sits on the cool side of the wheel. The nearest named color is Twilight Blue (#0A437A), ΔE 0.015 away. White text reads best on it, at 10.25:1.
| Hue family | Blues |
| Lightness | dark (38%) |
| Chroma | moderately saturated (0.116) |
| Temperature | cool |
| Nearest name | Twilight Blue (#0A437A) |
| Black text | 2.04:1 |
| White text | 10.25:1 |
Values
| HEX | #173F7E |
| RGB | rgb(23, 63, 126) |
| HSL | hsl(217, 69%, 29%) |
| OKLCH | oklch(37.8% 0.116 259.4) |
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 #173F7E | 10.25:1 | AAA | Lc -97.5 | Preferred for body text |
| Black text on #173F7E | 2.04:1 | Fails | Lc 10.5 | Not readable |
| #173F7E text on white | 10.25:1 | AAA | Lc 93.4 | Preferred for body text |
| #173F7E text on black | 2.04:1 | Fails | Lc -9.1 | 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
#E0EBFB
oklch(93.7% 0.025 257.6)
-
Step 200
200
#C7DAFA
oklch(88.4% 0.049 260.9)
-
Step 300
300
#9FC2F9
oklch(80.8% 0.087 259.3)
-
Step 400
400
#6AA0F6
oklch(70.6% 0.139 259.4)
-
Step 500
500
#4186F3
oklch(63.1% 0.178 259.3)
-
Step 600
600
#1F6CE2
oklch(55.6% 0.194 259.5)
-
Step 700
700
#115AC4
oklch(49.2% 0.179 259.3)
-
Step 800
800
#124A9E
oklch(42.7% 0.148 259.2)
-
Step 900
900 (this color)
#173F7E
oklch(37.8% 0.116 259.4)
-
Step 950
950
#0F254A
oklch(27% 0.074 260.2)
#173F7E 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) | #1B4680 | 0.021 |
| Deuteranopia (no green cones) | #003C7D | 0.017 |
| Tritanopia (no blue cones) | #004E58 | 0.090 |
| Achromatopsia (no color) | #414141 | 0.116 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #173F7E
#173F7E
oklch(37.8% 0.116 259.4)
- #583C00
#583C00
oklch(37.8% 0.079 79.1)
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 #173F7E, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Twilight Blue #0A437A ΔE 0.015
- Cobalt #1E488F ΔE 0.038
- Marine Blue #01386A ΔE 0.043
- Light Navy #155084 ΔE 0.050
- Deep Sea Blue #015482 ΔE 0.061
- Dusk Blue #26538D ΔE 0.065
- Dark Slate Blue #483D8B ΔE 0.067
- Prussian Blue #1D3557 ΔE 0.070
Use #173F7E 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.