#173BBD
Closest named color: Blue Blue (#2242C7). oklch(42.7% 0.206 265.4), rgb(23, 59, 189).
Aa
White text reads best on this color (8.76:1).
About this color
#173BBD is a dark, vivid blue. In OKLCH its lightness is 43%, its chroma 0.206 and its hue 265°. Its hue sits on the cool side of the wheel. The nearest named color is Blue Blue (#2242C7), ΔE 0.026 away. White text reads best on it, at 8.76:1.
| Hue family | Blues |
| Lightness | dark (43%) |
| Chroma | vivid (0.206) |
| Temperature | cool |
| Nearest name | Blue Blue (#2242C7) |
| Black text | 2.39:1 |
| White text | 8.76:1 |
Values
| HEX | #173BBD |
| RGB | rgb(23, 59, 189) |
| HSL | hsl(227, 78%, 42%) |
| OKLCH | oklch(42.7% 0.206 265.4) |
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 #173BBD | 8.76:1 | AAA | Lc -93.6 | Preferred for body text |
| Black text on #173BBD | 2.39:1 | Fails | Lc 15.0 | Not readable |
| #173BBD text on white | 8.76:1 | AAA | Lc 89.0 | Fine for body text |
| #173BBD text on black | 2.39:1 | Fails | Lc -13.2 | 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 800.
-
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
#C8D9FF
oklch(88.5% 0.056 266.2)
-
Step 300
300
#A3C0FF
oklch(80.9% 0.095 265.2)
-
Step 400
400
#729CFF
oklch(70.6% 0.153 265.4)
-
Step 500
500
#4E7FFF
oklch(63% 0.198 265.3)
-
Step 600
600
#2C5EFF
oklch(55.6% 0.244 265.3)
-
Step 700
700
#1B45EA
oklch(49% 0.249 265.4)
-
Step 800
800 (this color)
#173BBD
oklch(42.7% 0.206 265.4)
-
Step 900
900
#173595
oklch(37.6% 0.161 265.5)
-
Step 950
950
#0E2157
oklch(27.1% 0.101 265.3)
#173BBD 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) | #0053C1 | 0.054 |
| Deuteranopia (no green cones) | #0043BB | 0.017 |
| Tritanopia (no blue cones) | #005F77 | 0.157 |
| Achromatopsia (no color) | #4B4B4B | 0.206 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #173BBD
#173BBD
oklch(42.7% 0.206 265.4)
- #654A00
#654A00
oklch(42.7% 0.087 84.5)
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 #173BBD, closest first.
No curated palette has a color within ΔE 0.04 of #173BBD.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Blue Blue #2242C7 ΔE 0.026
- Sapphire #2138AB ΔE 0.031
- Majorelle Blue #3F37C9 ΔE 0.047
- True Blue #010FCC ΔE 0.066
- Indigo Blue #3A18B1 ΔE 0.066
- Ultramarine Blue #1805DB ΔE 0.070
- Medium Blue #0000CD ΔE 0.074
- Blue With A Hint Of Purple #533CC6 ΔE 0.077
Use #173BBD 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.