#178DE9
Closest named color: Dark Sky Blue (#448EE4). oklch(63.1% 0.168 249.2), rgb(23, 141, 233).
Aa
Black text reads best on this color (6.02:1).
About this color
#178DE9 is a medium-light, vivid blue. In OKLCH its lightness is 63%, its chroma 0.168 and its hue 249°. Its hue sits on the cool side of the wheel. The nearest named color is Dark Sky Blue (#448EE4), ΔE 0.025 away. Black text reads best on it, at 6.02:1.
| Hue family | Blues |
| Lightness | medium-light (63%) |
| Chroma | vivid (0.168) |
| Temperature | cool |
| Nearest name | Dark Sky Blue (#448EE4) |
| Black text | 6.02:1 |
| White text | 3.48:1 |
Values
| HEX | #178DE9 |
| RGB | rgb(23, 141, 233) |
| HSL | hsl(206, 83%, 50%) |
| OKLCH | oklch(63.1% 0.168 249.2) |
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 #178DE9 | 3.48:1 | AA large text | Lc -67.3 | Content text, not long reading |
| Black text on #178DE9 | 6.02:1 | AA | Lc 42.3 | Non-text elements, placeholder text |
| #178DE9 text on white | 3.48:1 | AA large text | Lc 61.8 | Content text, not long reading |
| #178DE9 text on black | 6.02:1 | AA | Lc -39.9 | Non-text elements, placeholder text |
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 500.
-
Step 50
50
#F0F6FD
oklch(97.1% 0.011 252.1)
-
Step 100
100
#DEECFA
oklch(93.7% 0.024 248.1)
-
Step 200
200
#C3DCF7
oklch(88.5% 0.046 250.4)
-
Step 300
300
#98C5F4
oklch(80.8% 0.082 250)
-
Step 400
400
#5AA6EF
oklch(70.8% 0.132 249.3)
-
Step 500
500 (this color)
#178DE9
oklch(63.1% 0.168 249.2)
-
Step 600
600
#0076C9
oklch(55.6% 0.155 249.4)
-
Step 700
700
#0063AA
oklch(49.1% 0.137 249.4)
-
Step 800
800
#00518C
oklch(42.7% 0.118 249.2)
-
Step 900
900
#004376
oklch(37.6% 0.105 249.5)
-
Step 950
950
#042846
oklch(27% 0.068 248.6)
#178DE9 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) | #5F93ED | 0.053 |
| Deuteranopia (no green cones) | #3D81E7 | 0.033 |
| Tritanopia (no blue cones) | #00A3B0 | 0.120 |
| Achromatopsia (no color) | #898989 | 0.168 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #178DE9
#178DE9
oklch(63.1% 0.168 249.2)
- #BE7700
#BE7700
oklch(63% 0.138 68.8)
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 #178DE9, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Dark Sky Blue #448EE4 ΔE 0.025
- Dodger Blue #1E90FF ΔE 0.033
- Chefchaouen Blue #4895EF ΔE 0.038
- Water Blue #0E87CC ΔE 0.045
- Soft Blue #6488EA ΔE 0.054
- Clear Blue #247AFD ΔE 0.060
- Cornflower Blue #6495ED ΔE 0.061
- Cool Blue #4984B8 ΔE 0.075
Use #178DE9 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.