#173991
Closest named color: Cobalt (#1E488F). oklch(38% 0.151 264.2), rgb(23, 57, 145).
Aa
White text reads best on this color (10.34:1).
About this color
#173991 is a dark, vivid blue. In OKLCH its lightness is 38%, its chroma 0.151 and its hue 264°. Its hue sits on the cool side of the wheel. The nearest named color is Cobalt (#1E488F), ΔE 0.042 away. White text reads best on it, at 10.34:1.
| Hue family | Blues |
| Lightness | dark (38%) |
| Chroma | vivid (0.151) |
| Temperature | cool |
| Nearest name | Cobalt (#1E488F) |
| Black text | 2.03:1 |
| White text | 10.34:1 |
Values
| HEX | #173991 |
| RGB | rgb(23, 57, 145) |
| HSL | hsl(223, 73%, 33%) |
| OKLCH | oklch(38% 0.151 264.2) |
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 #173991 | 10.34:1 | AAA | Lc -97.5 | Preferred for body text |
| Black text on #173991 | 2.03:1 | Fails | Lc 10.5 | Not readable |
| #173991 text on white | 10.34:1 | AAA | Lc 93.4 | Preferred for body text |
| #173991 text on black | 2.03:1 | 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
#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
#A2C0FF
oklch(80.9% 0.096 264.7)
-
Step 400
400
#709DFF
oklch(70.7% 0.152 264.2)
-
Step 500
500
#4A80FF
oklch(63.1% 0.198 264.2)
-
Step 600
600
#255FFF
oklch(55.6% 0.244 264.3)
-
Step 700
700
#174BE2
oklch(49.1% 0.234 264.3)
-
Step 800
800
#143FB6
oklch(42.6% 0.193 264.2)
-
Step 900
900 (this color)
#173991
oklch(38% 0.151 264.2)
-
Step 950
950
#0D2254
oklch(27% 0.095 263.9)
#173991 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) | #004694 | 0.034 |
| Deuteranopia (no green cones) | #003B8F | 0.013 |
| Tritanopia (no blue cones) | #00505F | 0.118 |
| Achromatopsia (no color) | #404040 | 0.151 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #173991
#173991
oklch(38% 0.151 264.2)
- #563E00
#563E00
oklch(38% 0.078 83.8)
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 #173991, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Cobalt #1E488F ΔE 0.042
- Sapphire #2138AB ΔE 0.044
- Twilight Blue #0A437A ΔE 0.049
- Blueberry #464196 ΔE 0.066
- Dark Slate Blue #483D8B ΔE 0.067
- Marine Blue #01386A ΔE 0.069
- Light Navy #155084 ΔE 0.070
- Royal #0C1793 ΔE 0.072
Use #173991 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.