#51BFF4
Closest named color: Deep Sky Blue (#00BFFF). oklch(76.3% 0.125 232.7), rgb(81, 191, 244).
Aa
Black text reads best on this color (10.10:1).
About this color
#51BFF4 is a medium-light, moderately saturated blue. In OKLCH its lightness is 76%, its chroma 0.125 and its hue 233°. Its hue sits on the cool side of the wheel. The nearest named color is Deep Sky Blue (#00BFFF), ΔE 0.030 away. Black text reads best on it, at 10.10:1.
| Hue family | Blues |
| Lightness | medium-light (76%) |
| Chroma | moderately saturated (0.125) |
| Temperature | cool |
| Nearest name | Deep Sky Blue (#00BFFF) |
| Black text | 10.10:1 |
| White text | 2.07:1 |
Values
| HEX | #51BFF4 |
| RGB | rgb(81, 191, 244) |
| HSL | hsl(200, 88%, 64%) |
| OKLCH | oklch(76.3% 0.125 232.7) |
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 #51BFF4 | 2.07:1 | Fails | Lc -44.8 | Non-text elements, placeholder text |
| Black text on #51BFF4 | 10.10:1 | AAA | Lc 63.6 | Content text, not long reading |
| #51BFF4 text on white | 2.07:1 | Fails | Lc 40.3 | Non-text elements, placeholder text |
| #51BFF4 text on black | 10.10:1 | AAA | Lc -62.0 | 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 300.
-
Step 50
50
#EBF8FF
oklch(97.1% 0.017 230.9)
-
Step 100
100
#D3EFFE
oklch(93.6% 0.036 231.1)
-
Step 200
200
#ADE2FF
oklch(88.6% 0.068 232.4)
-
Step 300
300 (this color)
#51BFF4
oklch(76.3% 0.125 232.7)
-
Step 400
400
#00AEEC
oklch(70.6% 0.146 233.1)
-
Step 500
500
#0095CB
oklch(63% 0.131 233.2)
-
Step 600
600
#007DAB
oklch(55.5% 0.115 233.2)
-
Step 700
700
#006990
oklch(49% 0.101 232.9)
-
Step 800
800
#005677
oklch(42.6% 0.088 233.1)
-
Step 900
900
#004864
oklch(37.8% 0.078 232.8)
-
Step 950
950
#002B3D
oklch(27.1% 0.055 231.9)
#51BFF4 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) | #A5BDF7 | 0.082 |
| Deuteranopia (no green cones) | #8EADF3 | 0.069 |
| Tritanopia (no blue cones) | #00CDD1 | 0.078 |
| Achromatopsia (no color) | #B4B4B4 | 0.125 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #51BFF4
#51BFF4
oklch(76.3% 0.125 232.7)
- #F09A63
#F09A63
oklch(76.2% 0.125 52.4)
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 #51BFF4, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Deep Sky Blue #00BFFF ΔE 0.030
- Vivid Sky Blue #4CC9F0 ΔE 0.030
- Bright Sky Blue #02CCFE ΔE 0.038
- Lightblue #7BC8F6 ΔE 0.045
- Sky #82CAFC ΔE 0.055
- Carolina Blue #8AB8FE ΔE 0.056
- Light Sky Blue #87CEFA ΔE 0.066
- Sky Blue #87CEEB ΔE 0.069
Use #51BFF4 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.