#51BDFF
Closest named color: Deep Sky Blue (#00BFFF). oklch(76.3% 0.136 239.1), rgb(81, 189, 255).
Aa
Black text reads best on this color (10.07:1).
About this color
#51BDFF is a medium-light, moderately saturated blue. In OKLCH its lightness is 76%, its chroma 0.136 and its hue 239°. Its hue sits on the cool side of the wheel. The nearest named color is Deep Sky Blue (#00BFFF), ΔE 0.027 away. Black text reads best on it, at 10.07:1.
| Hue family | Blues |
| Lightness | medium-light (76%) |
| Chroma | moderately saturated (0.136) |
| Temperature | cool |
| Nearest name | Deep Sky Blue (#00BFFF) |
| Black text | 10.07:1 |
| White text | 2.08:1 |
Values
| HEX | #51BDFF |
| RGB | rgb(81, 189, 255) |
| HSL | hsl(203, 100%, 66%) |
| OKLCH | oklch(76.3% 0.136 239.1) |
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 #51BDFF | 2.08:1 | Fails | Lc -45.0 | Large or bold text, headings |
| Black text on #51BDFF | 10.07:1 | AAA | Lc 63.5 | Content text, not long reading |
| #51BDFF text on white | 2.08:1 | Fails | Lc 40.4 | Non-text elements, placeholder text |
| #51BDFF text on black | 10.07:1 | AAA | Lc -61.9 | 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 300.
-
Step 50
50
#ECF7FF
oklch(97% 0.016 239.1)
-
Step 100
100
#D6EEFF
oklch(93.7% 0.034 238.7)
-
Step 200
200
#B3E0FF
oklch(88.5% 0.064 238.5)
-
Step 300
300 (this color)
#51BDFF
oklch(76.3% 0.136 239.1)
-
Step 400
400
#00ACF8
oklch(70.8% 0.159 238.8)
-
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
#00557E
oklch(42.8% 0.097 239.2)
-
Step 900
900
#004769
oklch(37.8% 0.084 238.3)
-
Step 950
950
#002A41
oklch(27.1% 0.061 239)
#51BDFF 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) | #9EBDFF | 0.073 |
| Deuteranopia (no green cones) | #86ACFE | 0.060 |
| Tritanopia (no blue cones) | #00CED4 | 0.093 |
| Achromatopsia (no color) | #B4B4B4 | 0.137 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #51BDFF
#51BDFF
oklch(76.3% 0.136 239.1)
- #F19B51
#F19B51
oklch(76.3% 0.136 59.2)
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 #51BDFF, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Deep Sky Blue #00BFFF ΔE 0.027
- Vivid Sky Blue #4CC9F0 ΔE 0.044
- Bright Sky Blue #02CCFE ΔE 0.045
- Carolina Blue #8AB8FE ΔE 0.050
- Lightblue #7BC8F6 ΔE 0.052
- Sky #82CAFC ΔE 0.059
- Light Sky Blue #87CEFA ΔE 0.071
- Pastel Blue #A2BFFE ΔE 0.079
Use #51BDFF 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.