#51ACFB
Closest named color: Deep Sky Blue (#00BFFF). oklch(72.4% 0.144 247.6), rgb(81, 172, 251).
Aa
Black text reads best on this color (8.64:1).
About this color
#51ACFB is a medium-light, vivid blue. In OKLCH its lightness is 72%, its chroma 0.144 and its hue 248°. Its hue sits on the cool side of the wheel. The nearest named color is Deep Sky Blue (#00BFFF), ΔE 0.053 away. Black text reads best on it, at 8.64:1.
| Hue family | Blues |
| Lightness | medium-light (72%) |
| Chroma | vivid (0.144) |
| Temperature | cool |
| Nearest name | Deep Sky Blue (#00BFFF) |
| Black text | 8.64:1 |
| White text | 2.42:1 |
Values
| HEX | #51ACFB |
| RGB | rgb(81, 172, 251) |
| HSL | hsl(208, 96%, 65%) |
| OKLCH | oklch(72.4% 0.144 247.6) |
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 #51ACFB | 2.42:1 | Fails | Lc -52.5 | Large or bold text, headings |
| Black text on #51ACFB | 8.64:1 | AAA | Lc 56.5 | Large or bold text, headings |
| #51ACFB text on white | 2.42:1 | Fails | Lc 47.5 | Large or bold text, headings |
| #51ACFB text on black | 8.64:1 | AAA | Lc -54.5 | 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
#EFF6FD
oklch(97% 0.012 248)
-
Step 100
100
#DDECFB
oklch(93.6% 0.026 248.1)
-
Step 200
200
#C0DDF9
oklch(88.5% 0.05 247.5)
-
Step 300
300
#91C6F8
oklch(80.8% 0.09 247.5)
-
Step 400
400 (this color)
#51ACFB
oklch(72.4% 0.144 247.6)
-
Step 500
500
#008EE9
oklch(63.1% 0.169 247.8)
-
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
#004474
oklch(37.7% 0.101 247.8)
-
Step 950
950
#002847
oklch(27% 0.072 247.4)
#51ACFB 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) | #89AFFE | 0.056 |
| Deuteranopia (no green cones) | #719FF9 | 0.041 |
| Tritanopia (no blue cones) | #00BFC8 | 0.109 |
| Achromatopsia (no color) | #A6A6A6 | 0.144 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #51ACFB
#51ACFB
oklch(72.4% 0.144 247.6)
- #E1922C
#E1922C
oklch(72.4% 0.145 67.5)
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 #51ACFB, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Deep Sky Blue #00BFFF ΔE 0.053
- Cornflower Blue #6495ED ΔE 0.060
- Chefchaouen Blue #4895EF ΔE 0.063
- Carolina Blue #8AB8FE ΔE 0.067
- Periwinkle Blue #8F99FB ΔE 0.075
- Dark Sky Blue #448EE4 ΔE 0.085
- Vivid Sky Blue #4CC9F0 ΔE 0.085
- Bright Sky Blue #02CCFE ΔE 0.086
Use #51ACFB 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.