#51B3FF
Closest named color: Deep Sky Blue (#00BFFF). oklch(74.1% 0.143 245), rgb(81, 179, 255).
Aa
Black text reads best on this color (9.24:1).
About this color
#51B3FF is a medium-light, vivid blue. In OKLCH its lightness is 74%, its chroma 0.143 and its hue 245°. Its hue sits on the cool side of the wheel. The nearest named color is Deep Sky Blue (#00BFFF), ΔE 0.039 away. Black text reads best on it, at 9.24:1.
| Hue family | Blues |
| Lightness | medium-light (74%) |
| Chroma | vivid (0.143) |
| Temperature | cool |
| Nearest name | Deep Sky Blue (#00BFFF) |
| Black text | 9.24:1 |
| White text | 2.27:1 |
Values
| HEX | #51B3FF |
| RGB | rgb(81, 179, 255) |
| HSL | hsl(206, 100%, 66%) |
| OKLCH | oklch(74.1% 0.143 245) |
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 #51B3FF | 2.27:1 | Fails | Lc -49.3 | Large or bold text, headings |
| Black text on #51B3FF | 9.24:1 | AAA | Lc 59.5 | Large or bold text, headings |
| #51B3FF text on white | 2.27:1 | Fails | Lc 44.5 | Non-text elements, placeholder text |
| #51B3FF text on black | 9.24:1 | AAA | Lc -57.6 | 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
#EFF7FD
oklch(97.2% 0.012 239.9)
-
Step 100
100
#DCECFA
oklch(93.5% 0.026 244.4)
-
Step 200
200
#BFDDF8
oklch(88.4% 0.049 245.6)
-
Step 300
300
#8FC7F7
oklch(80.9% 0.09 245.1)
-
Step 400
400 (this color)
#51B3FF
oklch(74.1% 0.143 245)
-
Step 500
500
#0090E2
oklch(63.1% 0.159 245)
-
Step 600
600
#0079BF
oklch(55.7% 0.14 245)
-
Step 700
700
#0065A1
oklch(49% 0.124 245.1)
-
Step 800
800
#005385
oklch(42.7% 0.107 244.8)
-
Step 900
900
#004570
oklch(37.7% 0.095 244.9)
-
Step 950
950
#002945
oklch(27.1% 0.068 244.5)
#51B3FF 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) | #91B5FF | 0.062 |
| Deuteranopia (no green cones) | #79A4FE | 0.049 |
| Tritanopia (no blue cones) | #00C5CE | 0.104 |
| Achromatopsia (no color) | #ACACAC | 0.143 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #51B3FF
#51B3FF
oklch(74.1% 0.143 245)
- #E89639
#E89639
oklch(74.1% 0.143 65.1)
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 #51B3FF, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Deep Sky Blue #00BFFF ΔE 0.039
- Carolina Blue #8AB8FE ΔE 0.056
- Bright Sky Blue #02CCFE ΔE 0.069
- Vivid Sky Blue #4CC9F0 ΔE 0.070
- Lightblue #7BC8F6 ΔE 0.075
- Cornflower Blue #6495ED ΔE 0.078
- Sky #82CAFC ΔE 0.082
- Chefchaouen Blue #4895EF ΔE 0.082
Use #51B3FF 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.