#288BD9
Closest named color: Water Blue (#0E87CC). oklch(61.9% 0.147 247.5), rgb(40, 139, 217).
Aa
Black text reads best on this color (5.78:1).
About this color
#288BD9 is a medium-dark, vivid blue. In OKLCH its lightness is 62%, its chroma 0.147 and its hue 247°. Its hue sits on the cool side of the wheel. The nearest named color is Water Blue (#0E87CC), ΔE 0.025 away. Black text reads best on it, at 5.78:1.
| Hue family | Blues |
| Lightness | medium-dark (62%) |
| Chroma | vivid (0.147) |
| Temperature | cool |
| Nearest name | Water Blue (#0E87CC) |
| Black text | 5.78:1 |
| White text | 3.62:1 |
Values
| HEX | #288BD9 |
| RGB | rgb(40, 139, 217) |
| HSL | hsl(206, 70%, 50%) |
| OKLCH | oklch(61.9% 0.147 247.5) |
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 #288BD9 | 3.62:1 | AA large text | Lc -68.9 | Content text, not long reading |
| Black text on #288BD9 | 5.78:1 | AA | Lc 40.6 | Non-text elements, placeholder text |
| #288BD9 text on white | 3.62:1 | AA large text | Lc 63.4 | Content text, not long reading |
| #288BD9 text on black | 5.78:1 | AA | Lc -38.2 | 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
#F1F6FC
oklch(97.1% 0.01 252.8)
-
Step 100
100
#DFECF7
oklch(93.7% 0.02 243.4)
-
Step 200
200
#C5DCF3
oklch(88.5% 0.04 248.3)
-
Step 300
300
#9CC6ED
oklch(81% 0.071 246.8)
-
Step 400
400
#62A6E5
oklch(70.6% 0.116 248)
-
Step 500
500 (this color)
#288BD9
oklch(61.9% 0.147 247.5)
-
Step 600
600
#0077C4
oklch(55.5% 0.148 247.6)
-
Step 700
700
#0064A6
oklch(49.1% 0.131 247.6)
-
Step 800
800
#005289
oklch(42.7% 0.113 247.3)
-
Step 900
900
#064471
oklch(37.6% 0.096 247.4)
-
Step 950
950
#082842
oklch(26.9% 0.061 247.3)
#288BD9 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) | #668FDC | 0.054 |
| Deuteranopia (no green cones) | #4C7FD8 | 0.037 |
| Tritanopia (no blue cones) | #009EA8 | 0.105 |
| Achromatopsia (no color) | #868686 | 0.147 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #288BD9
#288BD9
oklch(61.9% 0.147 247.5)
- #BB7300
#BB7300
oklch(61.9% 0.136 67.4)
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 #288BD9, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Water Blue #0E87CC ΔE 0.025
- Dark Sky Blue #448EE4 ΔE 0.027
- Chefchaouen Blue #4895EF ΔE 0.048
- Cool Blue #4984B8 ΔE 0.052
- Dodger Blue #1E90FF ΔE 0.057
- Steel Blue #4682B4 ΔE 0.057
- Soft Blue #6488EA ΔE 0.057
- Windows Blue #3778BF ΔE 0.059
Use #288BD9 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.