#173B7B
Closest named color: Twilight Blue (#0A437A). oklch(36.6% 0.117 260.9), rgb(23, 59, 123).
Aa
White text reads best on this color (10.78:1).
About this color
#173B7B is a dark, moderately saturated blue. In OKLCH its lightness is 37%, its chroma 0.117 and its hue 261°. Its hue sits on the cool side of the wheel. The nearest named color is Twilight Blue (#0A437A), ΔE 0.023 away. White text reads best on it, at 10.78:1.
| Hue family | Blues |
| Lightness | dark (37%) |
| Chroma | moderately saturated (0.117) |
| Temperature | cool |
| Nearest name | Twilight Blue (#0A437A) |
| Black text | 1.94:1 |
| White text | 10.78:1 |
Values
| HEX | #173B7B |
| RGB | rgb(23, 59, 123) |
| HSL | hsl(218, 68%, 29%) |
| OKLCH | oklch(36.6% 0.117 260.9) |
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 #173B7B | 10.78:1 | AAA | Lc -98.5 | Preferred for body text |
| Black text on #173B7B | 1.94:1 | Fails | Lc 9.3 | Not readable |
| #173B7B text on white | 10.78:1 | AAA | Lc 94.6 | Preferred for body text |
| #173B7B text on black | 1.94:1 | Fails | Lc -8.0 | 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
#F1F6FE
oklch(97.2% 0.012 259.8)
-
Step 100
100
#E0EAFB
oklch(93.5% 0.025 261.1)
-
Step 200
200
#C7DAFA
oklch(88.4% 0.049 260.9)
-
Step 300
300
#A1C2FA
oklch(81% 0.087 260.8)
-
Step 400
400
#6DA0F7
oklch(70.8% 0.139 260.5)
-
Step 500
500
#4685F4
oklch(63.2% 0.179 260.8)
-
Step 600
600
#276BE3
oklch(55.6% 0.195 260.9)
-
Step 700
700
#1A58C5
oklch(49% 0.182 260.9)
-
Step 800
800
#18499F
oklch(42.7% 0.15 260.8)
-
Step 900
900 (this color)
#173B7B
oklch(36.6% 0.117 260.9)
-
Step 950
950
#10254A
oklch(27% 0.074 260.8)
#173B7B 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) | #14427D | 0.020 |
| Deuteranopia (no green cones) | #00397A | 0.016 |
| Tritanopia (no blue cones) | #004A55 | 0.090 |
| Achromatopsia (no color) | #3D3D3D | 0.117 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #173B7B
#173B7B
oklch(36.6% 0.117 260.9)
- #533A00
#533A00
oklch(36.7% 0.076 81.4)
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 #173B7B, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Twilight Blue #0A437A ΔE 0.023
- Marine Blue #01386A ΔE 0.035
- Cobalt #1E488F ΔE 0.049
- Light Navy #155084 ΔE 0.062
- Marine #042E60 ΔE 0.062
- Prussian Blue #1D3557 ΔE 0.062
- Dark Slate Blue #483D8B ΔE 0.072
- Deep Sea Blue #015482 ΔE 0.072
Use #173B7B 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.