#51BBF0
Closest named color: Deep Sky Blue (#00BFFF). oklch(75.2% 0.123 233.6), rgb(81, 187, 240).
Aa
Black text reads best on this color (9.71:1).
About this color
#51BBF0 is a medium-light, moderately saturated blue. In OKLCH its lightness is 75%, its chroma 0.123 and its hue 234°. Its hue sits on the cool side of the wheel. The nearest named color is Deep Sky Blue (#00BFFF), ΔE 0.031 away. Black text reads best on it, at 9.71:1.
| Hue family | Blues |
| Lightness | medium-light (75%) |
| Chroma | moderately saturated (0.123) |
| Temperature | cool |
| Nearest name | Deep Sky Blue (#00BFFF) |
| Black text | 9.71:1 |
| White text | 2.16:1 |
Values
| HEX | #51BBF0 |
| RGB | rgb(81, 187, 240) |
| HSL | hsl(200, 84%, 63%) |
| OKLCH | oklch(75.2% 0.123 233.6) |
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 #51BBF0 | 2.16:1 | Fails | Lc -46.9 | Large or bold text, headings |
| Black text on #51BBF0 | 9.71:1 | AAA | Lc 61.8 | Content text, not long reading |
| #51BBF0 text on white | 2.16:1 | Fails | Lc 42.2 | Non-text elements, placeholder text |
| #51BBF0 text on black | 9.71:1 | AAA | Lc -60.0 | Content text, not long reading |
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
#EFF7FB
oklch(97.1% 0.01 228.9)
-
Step 100
100
#DCEDF7
oklch(93.6% 0.023 233.4)
-
Step 200
200
#BEDFF1
oklch(88.5% 0.043 231.8)
-
Step 300
300
#8ECAEB
oklch(81% 0.077 233.1)
-
Step 400
400 (this color)
#51BBF0
oklch(75.2% 0.123 233.6)
-
Step 500
500
#0095CC
oklch(63.1% 0.132 233.7)
-
Step 600
600
#007DAC
oklch(55.5% 0.116 233.8)
-
Step 700
700
#006991
oklch(49% 0.102 233.6)
-
Step 800
800
#005678
oklch(42.7% 0.089 233.9)
-
Step 900
900
#004864
oklch(37.8% 0.078 232.8)
-
Step 950
950
#002A3D
oklch(26.9% 0.056 233.8)
#51BBF0 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) | #A1B9F3 | 0.079 |
| Deuteranopia (no green cones) | #8BA9EF | 0.067 |
| Tritanopia (no blue cones) | #00C9CD | 0.079 |
| Achromatopsia (no color) | #B0B0B0 | 0.123 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #51BBF0
#51BBF0
oklch(75.2% 0.123 233.6)
- #EB9860
#EB9860
oklch(75.2% 0.123 53.7)
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 #51BBF0, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Deep Sky Blue #00BFFF ΔE 0.031
- Vivid Sky Blue #4CC9F0 ΔE 0.039
- Bright Sky Blue #02CCFE ΔE 0.047
- Lightblue #7BC8F6 ΔE 0.054
- Carolina Blue #8AB8FE ΔE 0.058
- Sky #82CAFC ΔE 0.064
- Light Sky Blue #87CEFA ΔE 0.075
- Sky Blue #87CEEB ΔE 0.076
Use #51BBF0 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.