#173C9B
Closest named color: Sapphire (#2138AB). oklch(39.6% 0.161 264.1), rgb(23, 60, 155).
Aa
White text reads best on this color (9.73:1).
About this color
#173C9B is a dark, vivid blue. In OKLCH its lightness is 40%, its chroma 0.161 and its hue 264°. Its hue sits on the cool side of the wheel. The nearest named color is Sapphire (#2138AB), ΔE 0.028 away. White text reads best on it, at 9.73:1.
| Hue family | Blues |
| Lightness | dark (40%) |
| Chroma | vivid (0.161) |
| Temperature | cool |
| Nearest name | Sapphire (#2138AB) |
| Black text | 2.15:1 |
| White text | 9.73:1 |
Values
| HEX | #173C9B |
| RGB | rgb(23, 60, 155) |
| HSL | hsl(223, 74%, 35%) |
| OKLCH | oklch(39.6% 0.161 264.1) |
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 #173C9B | 9.73:1 | AAA | Lc -96.2 | Preferred for body text |
| Black text on #173C9B | 2.15:1 | Fails | Lc 12.0 | Not readable |
| #173C9B text on white | 9.73:1 | AAA | Lc 91.9 | Preferred for body text |
| #173C9B text on black | 2.15:1 | Fails | Lc -10.5 | 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
#C7DAFF
oklch(88.6% 0.055 263.7)
-
Step 300
300
#A1C0FF
oklch(80.8% 0.096 264.1)
-
Step 400
400
#6F9DFF
oklch(70.7% 0.152 263.9)
-
Step 500
500
#4A80FF
oklch(63.1% 0.198 264.2)
-
Step 600
600
#245FFF
oklch(55.6% 0.245 264.2)
-
Step 700
700
#0F47EA
oklch(49.1% 0.249 264)
-
Step 800
800
#0F3CBD
oklch(42.7% 0.206 264.1)
-
Step 900
900 (this color)
#173C9B
oklch(39.6% 0.161 264.1)
-
Step 950
950
#0B2157
oklch(27% 0.102 264)
#173C9B 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) | #004A9E | 0.035 |
| Deuteranopia (no green cones) | #003E99 | 0.012 |
| Tritanopia (no blue cones) | #005565 | 0.125 |
| Achromatopsia (no color) | #444444 | 0.161 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #173C9B
#173C9B
oklch(39.6% 0.161 264.1)
- #5B4200
#5B4200
oklch(39.6% 0.081 84.1)
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 #173C9B, closest first.
No curated palette has a color within ΔE 0.04 of #173C9B.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Sapphire #2138AB ΔE 0.028
- Cobalt #1E488F ΔE 0.040
- Twilight Blue #0A437A ΔE 0.060
- Blueberry #464196 ΔE 0.061
- Dark Slate Blue #483D8B ΔE 0.067
- Light Navy #155084 ΔE 0.070
- Dusk Blue #26538D ΔE 0.072
- Indigo Blue #3A18B1 ΔE 0.074
Use #173C9B 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.