#173F70
Closest named color: Twilight Blue (#0A437A). oklch(36.7% 0.096 255.3), rgb(23, 63, 112).
Aa
White text reads best on this color (10.59:1).
About this color
#173F70 is a dark, moderately saturated blue. In OKLCH its lightness is 37%, its chroma 0.096 and its hue 255°. Its hue sits on the cool side of the wheel. The nearest named color is Twilight Blue (#0A437A), ΔE 0.019 away. White text reads best on it, at 10.59:1.
| Hue family | Blues |
| Lightness | dark (37%) |
| Chroma | moderately saturated (0.096) |
| Temperature | cool |
| Nearest name | Twilight Blue (#0A437A) |
| Black text | 1.98:1 |
| White text | 10.59:1 |
Values
| HEX | #173F70 |
| RGB | rgb(23, 63, 112) |
| HSL | hsl(213, 66%, 26%) |
| OKLCH | oklch(36.7% 0.096 255.3) |
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 #173F70 | 10.59:1 | AAA | Lc -98.3 | Preferred for body text |
| Black text on #173F70 | 1.98:1 | Fails | Lc 9.7 | Not readable |
| #173F70 text on white | 10.59:1 | AAA | Lc 94.3 | Preferred for body text |
| #173F70 text on black | 1.98:1 | Fails | Lc -8.3 | 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
#F1F6FC
oklch(97.1% 0.01 252.8)
-
Step 100
100
#E1EBF8
oklch(93.6% 0.021 254.9)
-
Step 200
200
#C8DBF4
oklch(88.5% 0.04 255.3)
-
Step 300
300
#A2C3EF
oklch(80.8% 0.072 255.7)
-
Step 400
400
#6FA3E7
oklch(70.7% 0.115 255.5)
-
Step 500
500
#468AE0
oklch(63% 0.147 255.5)
-
Step 600
600
#2572CE
oklch(55.5% 0.16 255.6)
-
Step 700
700
#175FB2
oklch(49% 0.149 255.5)
-
Step 800
800
#164E90
oklch(42.6% 0.123 255.4)
-
Step 900
900 (this color)
#173F70
oklch(36.7% 0.096 255.3)
-
Step 950
950
#102743
oklch(27% 0.06 254.6)
#173F70 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) | #274372 | 0.022 |
| Deuteranopia (no green cones) | #183B6F | 0.012 |
| Tritanopia (no blue cones) | #004B52 | 0.074 |
| Achromatopsia (no color) | #3F3F3F | 0.096 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #173F70
#173F70
oklch(36.7% 0.096 255.3)
- #563800
#563800
oklch(36.7% 0.077 75.5)
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 #173F70, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Twilight Blue #0A437A ΔE 0.019
- Marine Blue #01386A ΔE 0.029
- Prussian Blue #1D3557 ΔE 0.048
- Dark Grey Blue #29465B ΔE 0.050
- Light Navy #155084 ΔE 0.057
- Cobalt #1E488F ΔE 0.057
- Dark Blue Grey #1F3B4D ΔE 0.060
- Marine #042E60 ΔE 0.061
Use #173F70 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.