#51B2EE
Closest named color: Deep Sky Blue (#00BFFF). oklch(73.1% 0.126 239), rgb(81, 178, 238).
Aa
Black text reads best on this color (8.95:1).
About this color
#51B2EE is a medium-light, moderately saturated blue. In OKLCH its lightness is 73%, its chroma 0.126 and its hue 239°. Its hue sits on the cool side of the wheel. The nearest named color is Deep Sky Blue (#00BFFF), ΔE 0.041 away. Black text reads best on it, at 8.95:1.
| Hue family | Blues |
| Lightness | medium-light (73%) |
| Chroma | moderately saturated (0.126) |
| Temperature | cool |
| Nearest name | Deep Sky Blue (#00BFFF) |
| Black text | 8.95:1 |
| White text | 2.34:1 |
Values
| HEX | #51B2EE |
| RGB | rgb(81, 178, 238) |
| HSL | hsl(203, 82%, 63%) |
| OKLCH | oklch(73.1% 0.126 239) |
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 #51B2EE | 2.34:1 | Fails | Lc -50.9 | Large or bold text, headings |
| Black text on #51B2EE | 8.95:1 | AAA | Lc 58.0 | Large or bold text, headings |
| #51B2EE text on white | 2.34:1 | Fails | Lc 46.0 | Large or bold text, headings |
| #51B2EE text on black | 8.95:1 | AAA | Lc -56.1 | Large or bold text, headings |
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 400.
-
Step 50
50
#EFF7FC
oklch(97.2% 0.011 234.8)
-
Step 100
100
#DDECF8
oklch(93.5% 0.023 241.9)
-
Step 200
200
#C0DEF3
oklch(88.5% 0.043 238.5)
-
Step 300
300
#91C8EE
oklch(80.8% 0.079 239.1)
-
Step 400
400 (this color)
#51B2EE
oklch(73.1% 0.126 239)
-
Step 500
500
#0093D5
oklch(63.1% 0.142 238.9)
-
Step 600
600
#007BB4
oklch(55.5% 0.126 239.3)
-
Step 700
700
#006898
oklch(49.2% 0.11 238.7)
-
Step 800
800
#00557D
oklch(42.7% 0.096 238.5)
-
Step 900
900
#004769
oklch(37.8% 0.084 238.3)
-
Step 950
950
#002A41
oklch(27.1% 0.061 239)
#51B2EE 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) | #96B2F1 | 0.069 |
| Deuteranopia (no green cones) | #81A2ED | 0.058 |
| Tritanopia (no blue cones) | #00C1C7 | 0.087 |
| Achromatopsia (no color) | #A9A9A9 | 0.126 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #51B2EE
#51B2EE
oklch(73.1% 0.126 239)
- #E29351
#E29351
oklch(73.1% 0.126 58.8)
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 #51B2EE, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Deep Sky Blue #00BFFF ΔE 0.041
- Vivid Sky Blue #4CC9F0 ΔE 0.063
- Carolina Blue #8AB8FE ΔE 0.063
- Bright Sky Blue #02CCFE ΔE 0.069
- Turquoise Blue #06B1C4 ΔE 0.074
- Lightblue #7BC8F6 ΔE 0.074
- Cornflower Blue #6495ED ΔE 0.078
- Chefchaouen Blue #4895EF ΔE 0.082
Use #51B2EE 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.